{"course":{"slug":"image-editing","title":"Editing an Image","url":"https://addaly.com/learn/image-editing","level":"beginner","track":"create"},"lesson":{"slug":"when-the-file-gets-too-big","title":"Working on a laptop that cannot hold the job","url":"https://addaly.com/learn/image-editing/when-the-file-gets-too-big","position":20,"of":78,"minutes":9,"answer":"A slow document has four separable causes (pixel count, layer count, smart-filter re-rendering and scratch thrashing) and the fixes run from hiding groups and stamping checkpoints up to splitting the job into two documents.","keyIdea":"A slow document has four separable causes (pixel count, layer count, smart-filter re-rendering and scratch thrashing) and the fixes run from hiding groups and stamping checkpoints up to splitting the job into two documents, with browser-based tools hitting a hard memory ceiling rather than degrading gradually."},"body":{"format":"markdown","text":"## Four separate causes of a slow document\n\n\"It has got slow\" is four different problems, and the fix differs for each. Diagnose before you start deleting work.\n\n**1. Pixel count.** A 50-megapixel image in 16-bit is 300 MB per full-resolution layer before anything else. Every operation touches all of it.\n\n> Figure: One full-resolution layer, before anything else is open. Bars (MB): 12 megapixels, 8 bits 36; 12 megapixels, 16 bits 72; 24 megapixels, 16 bits 144; 50 megapixels, 8 bits 150; 50 megapixels, 16 bits 300. Three channels, one or two bytes each, times the pixel count. Twenty adjustment layers re-composite all of that on every brushstroke. Photopea lives inside a browser tab with two to four gigabytes and no scratch disk, so it stops rather than slowing; GIMP and Krita swap to disk and degrade gradually.\n\n**2. Layer count and re-compositing.** Change one layer and the application re-composites everything above it. Twenty adjustment layers means twenty operations per brushstroke.\n\n**3. Smart filters re-rendering.** Each smart filter re-runs on every change to its smart object. A Gaussian blur at radius 200 on a large smart object is seconds of work, repeated constantly.\n\n**4. Scratch thrashing.** The previous lesson's problem. Watch the efficiency indicator: Photoshop shows it at the bottom of the window if you set the status bar to *Efficiency*. Below 100 per cent means it is using disk; below 60 per cent means it is mostly using disk and you will feel it.\n\n## The five fixes, from cheapest to most drastic\n\n**Turn off what you are not looking at.** Hide the groups you are not working on. Hidden layers still take memory but are not composited, which addresses cause 2 immediately.\n\n**Rasterise finished smart objects.** Once the retouch inside a smart object is done and the transform settled, rasterising removes the re-render cost permanently. Save a version first.\n\n**Stamp a checkpoint.** Ctrl/Cmd+Alt+Shift+E to flatten the visible result onto one layer, then hide everything below it and carry on above. The stack is preserved for a revision and costs nothing to composite while hidden. Name it with the date.\n\n**Split the job.** Do the retouching in one document at full resolution and save a flattened TIFF. Do the compositing in a second document that places that TIFF. Two 400 MB documents open one at a time beat one 900 MB document open all the time.\n\n**Work at reduced size, apply at full.** For work that is about placement rather than detail (a rough composite, deciding a crop, testing a grade) do it on a half-size copy. Curves, Levels, Hue/Saturation and most adjustment settings copy across to the full-size file unchanged, because they are functions of tone rather than of pixels. Masks and brushwork do not; those have to be done at full size.\n\n## Photopea's ceiling, stated plainly\n\nPhotopea runs in a browser tab, so it lives inside that tab's memory allocation. In practice this is around 2 to 4 GB depending on the browser and the machine, and there is no scratch disk to overflow into. When it runs out, the tab does not slow down gracefully: it stops or reloads.\n\nWhat that means in practice: Photopea handles a 24-megapixel photograph with fifteen layers comfortably and will not handle a 100-megapixel poster with forty. Save often, and for large documents use a desktop application. This is not a criticism of Photopea; it is the architecture.\n\nGIMP and Krita both have real tile-based memory management and swap to disk, so they degrade gradually instead. On a machine with 8 GB of RAM, GIMP on a large file will be slow and will keep working, which is often the more useful behaviour.\n\n## Working on low-end hardware\n\nA large part of this readership is on a laptop with 4 to 8 GB of RAM, integrated graphics, and a nearly full drive. That is a real constraint and it is workable.\n\n- **Downsize at the start, deliberately.** If the delivery is a 2,000-pixel web image, working on a 24-megapixel original is not producing quality, it is producing lag. Resize to 3,000 pixels on the long edge before you begin and you have ample margin.\n- **8-bit unless the job needs 16.** Tonal stretching on a gradient needs 16; a product cut-out with modest adjustments does not.\n- **Use GIMP or Krita rather than a browser tool** for anything large, for the memory reason above.\n- **Close the browser.** Thirty tabs is two gigabytes.\n- **An external SSD over USB 3** for scratch and files costs about £30 for 500 GB and is the single best value upgrade for this work. More RAM is better and is often soldered on modern laptops; a fast external drive is never soldered.\n\n## On a phone\n\nEntirely viable for a real class of work, and worth knowing the limits. Snapseed keeps an editable stack and is free with no ads. Lightroom mobile's free tier develops raw and DNG parametrically, which is non-destructive. Photopea runs in a mobile browser and is painful to use on a small screen but works. Krita has an Android build.\n\nWhat a phone does not do: precise masking at 100 per cent zoom, colour-managed print work, or anything with a deep layer stack. What it does well: developing a raw file, straightening, cropping, global tone and colour, and a quick cut-out. For a market trader photographing stock, that covers most of the job.\n\n## The limit worth accepting\n\nSome jobs need hardware you do not have. A 200-megapixel architectural composite with sixty layers is not going to happen on an eight-gigabyte laptop, and no amount of technique changes that.\n\nWhen you meet one, the answer is to reduce the scope of what is open at once (split the document, work in sections, flatten aggressively with versions saved) or to rent time on a better machine. What does not work is spending the day fighting an application and delivering late. Recognising the ceiling early is a professional skill, and telling the client on day one rather than day five is the part that matters."},"check":{"question":"An editor working in Photopea on a 90-megapixel poster finds the tab reloads without warning after about twenty minutes, losing unsaved work. What is the correct reading of this?","options":[{"text":"The document's scratch file has filled the system drive, and freeing disk space will stop the reloads.","correct":false,"tempting":"Applies a desktop diagnosis to a tool that has no scratch disk: a browser tab cannot overflow onto disk the way a native application does."},{"text":"The internet connection is dropping, and Photopea reloads when it cannot reach its server.","correct":false,"tempting":"Assumes server dependence that does not match the tool's behaviour: Photopea does the editing locally in the tab and continues working through a connection loss."},{"text":"The document has exceeded the browser tab's memory allocation, which has no disk overflow, so the tab is terminated rather than slowed.","correct":true},{"text":"Too many layers are set to a blend mode other than Normal, forcing isolated compositing that the browser cannot handle.","correct":false,"tempting":"Picks a real cost driver as the whole explanation: isolated group compositing raises memory use, but the abrupt termination is the allocation ceiling rather than any single feature."}]},"prev":{"slug":"setting-up-to-work-fast","title":"Eleven shortcuts and a scratch disk","url":"https://addaly.com/learn/image-editing/setting-up-to-work-fast"},"next":{"slug":"selections-and-edges","title":"Selections are easy until you reach hair","url":"https://addaly.com/learn/image-editing/selections-and-edges"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'Working on a laptop that cannot hold the job', in Editing an Image. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/image-editing/when-the-file-gets-too-big (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Working on a laptop that cannot hold the job","courseTitle":"Editing an Image","module":{"index":2,"slug":"the-non-destructive-workshop","title":"The non-destructive workshop"},"answer":null,"keyIdea":"A slow document has four separable causes (pixel count, layer count, smart-filter re-rendering and scratch thrashing) and the fixes run from hiding groups and stamping checkpoints up to splitting the job into two documents, with browser-based tools hitting a hard memory ceiling rather than degrading gradually.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"type":"bars","unit":"MB","title":"One full-resolution layer, before anything else is open","series":[{"label":"12 megapixels, 8 bits","value":36},{"label":"12 megapixels, 16 bits","value":72},{"label":"24 megapixels, 16 bits","value":144},{"label":"50 megapixels, 8 bits","value":150},{"label":"50 megapixels, 16 bits","value":300,"highlight":true}],"caption":"Three channels, one or two bytes each, times the pixel count. Twenty adjustment layers re-composite all of that on every brushstroke. Photopea lives inside a browser tab with two to four gigabytes and no scratch disk, so it stops rather than slowing; GIMP and Krita swap to disk and degrade gradually."},"alt":"Figure: One full-resolution layer, before anything else is open. Bars (MB): 12 megapixels, 8 bits 36; 12 megapixels, 16 bits 72; 24 megapixels, 16 bits 144; 50 megapixels, 8 bits 150; 50 megapixels, 16 bits 300. Three channels, one or two bytes each, times the pixel count. Twenty adjustment layers re-composite all of that on every brushstroke. Photopea lives inside a browser tab with two to four gigabytes and no scratch disk, so it stops rather than slowing; GIMP and Krita swap to disk and degrade gradually."}},"blocks":[{"t":"h2","id":"four-separate-causes-of-a-slow-document","runs":[{"text":"Four separate causes of a slow document"}]},{"t":"p","runs":[{"text":"“It has got slow” is four different problems, and the fix differs for each. Diagnose before you start deleting work."}]},{"t":"p","runs":[{"text":"1. Pixel count.","b":true},{"text":" A 50-megapixel image in 16-bit is 300 MB per full-resolution layer before anything else. Every operation touches all of it."}]},{"t":"p","runs":[{"text":"2. Layer count and re-compositing.","b":true},{"text":" Change one layer and the application re-composites everything above it. Twenty adjustment layers means twenty operations per brushstroke."}]},{"t":"p","runs":[{"text":"3. Smart filters re-rendering.","b":true},{"text":" Each smart filter re-runs on every change to its smart object. A Gaussian blur at radius 200 on a large smart object is seconds of work, repeated constantly."}]},{"t":"p","runs":[{"text":"4. Scratch thrashing.","b":true},{"text":" The previous lesson’s problem. Watch the efficiency indicator: Photoshop shows it at the bottom of the window if you set the status bar to "},{"text":"Efficiency","i":true},{"text":". Below 100 per cent means it is using disk; below 60 per cent means it is mostly using disk and you will feel it."}]},{"t":"h2","id":"the-five-fixes-from-cheapest-to-most-drastic","runs":[{"text":"The five fixes, from cheapest to most drastic"}]},{"t":"p","runs":[{"text":"Turn off what you are not looking at.","b":true},{"text":" Hide the groups you are not working on. Hidden layers still take memory but are not composited, which addresses cause 2 immediately."}]},{"t":"p","runs":[{"text":"Rasterise finished smart objects.","b":true},{"text":" Once the retouch inside a smart object is done and the transform settled, rasterising removes the re-render cost permanently. Save a version first."}]},{"t":"p","runs":[{"text":"Stamp a checkpoint.","b":true},{"text":" Ctrl/Cmd+Alt+Shift+E to flatten the visible result onto one layer, then hide everything below it and carry on above. The stack is preserved for a revision and costs nothing to composite while hidden. Name it with the date."}]},{"t":"p","runs":[{"text":"Split the job.","b":true},{"text":" Do the retouching in one document at full resolution and save a flattened TIFF. Do the compositing in a second document that places that TIFF. Two 400 MB documents open one at a time beat one 900 MB document open all the time."}]},{"t":"p","runs":[{"text":"Work at reduced size, apply at full.","b":true},{"text":" For work that is about placement rather than detail (a rough composite, deciding a crop, testing a grade) do it on a half-size copy. Curves, Levels, Hue/Saturation and most adjustment settings copy across to the full-size file unchanged, because they are functions of tone rather than of pixels. Masks and brushwork do not; those have to be done at full size."}]},{"t":"h2","id":"photopea-s-ceiling-stated-plainly","runs":[{"text":"Photopea’s ceiling, stated plainly"}]},{"t":"p","runs":[{"text":"Photopea runs in a browser tab, so it lives inside that tab’s memory allocation. In practice this is around 2 to 4 GB depending on the browser and the machine, and there is no scratch disk to overflow into. When it runs out, the tab does not slow down gracefully: it stops or reloads."}]},{"t":"p","runs":[{"text":"What that means in practice: Photopea handles a 24-megapixel photograph with fifteen layers comfortably and will not handle a 100-megapixel poster with forty. Save often, and for large documents use a desktop application. This is not a criticism of Photopea; it is the architecture."}]},{"t":"p","runs":[{"text":"GIMP and Krita both have real tile-based memory management and swap to disk, so they degrade gradually instead. On a machine with 8 GB of RAM, GIMP on a large file will be slow and will keep working, which is often the more useful behaviour."}]},{"t":"h2","id":"working-on-low-end-hardware","runs":[{"text":"Working on low-end hardware"}]},{"t":"p","runs":[{"text":"A large part of this readership is on a laptop with 4 to 8 GB of RAM, integrated graphics, and a nearly full drive. That is a real constraint and it is workable."}]},{"t":"ul","items":[[{"text":"Downsize at the start, deliberately.","b":true},{"text":" If the delivery is a 2,000-pixel web image, working on a 24-megapixel original is not producing quality, it is producing lag. Resize to 3,000 pixels on the long edge before you begin and you have ample margin."}],[{"text":"8-bit unless the job needs 16.","b":true},{"text":" Tonal stretching on a gradient needs 16; a product cut-out with modest adjustments does not."}],[{"text":"Use GIMP or Krita rather than a browser tool","b":true},{"text":" for anything large, for the memory reason above."}],[{"text":"Close the browser.","b":true},{"text":" Thirty tabs is two gigabytes."}],[{"text":"An external SSD over USB 3","b":true},{"text":" for scratch and files costs about £30 for 500 GB and is the single best value upgrade for this work. More RAM is better and is often soldered on modern laptops; a fast external drive is never soldered."}]]},{"t":"h2","id":"on-a-phone","runs":[{"text":"On a phone"}]},{"t":"p","runs":[{"text":"Entirely viable for a real class of work, and worth knowing the limits. Snapseed keeps an editable stack and is free with no ads. Lightroom mobile’s free tier develops raw and DNG parametrically, which is non-destructive. Photopea runs in a mobile browser and is painful to use on a small screen but works. Krita has an Android build."}]},{"t":"p","runs":[{"text":"What a phone does not do: precise masking at 100 per cent zoom, colour-managed print work, or anything with a deep layer stack. What it does well: developing a raw file, straightening, cropping, global tone and colour, and a quick cut-out. For a market trader photographing stock, that covers most of the job."}]},{"t":"h2","id":"the-limit-worth-accepting","runs":[{"text":"The limit worth accepting"}],"role":"limit"},{"t":"p","runs":[{"text":"Some jobs need hardware you do not have. A 200-megapixel architectural composite with sixty layers is not going to happen on an eight-gigabyte laptop, and no amount of technique changes that."}]},{"t":"p","runs":[{"text":"When you meet one, the answer is to reduce the scope of what is open at once (split the document, work in sections, flatten aggressively with versions saved) or to rent time on a better machine. What does not work is spending the day fighting an application and delivering late. Recognising the ceiling early is a professional skill, and telling the client on day one rather than day five is the part that matters."}]}],"check":{"question":[{"text":"An editor working in Photopea on a 90-megapixel poster finds the tab reloads without warning after about twenty minutes, losing unsaved work. What is the correct reading of this?"}],"options":[{"text":[{"text":"The document’s scratch file has filled the system drive, and freeing disk space will stop the reloads."}],"correct":false,"tempting":[{"text":"Applies a desktop diagnosis to a tool that has no scratch disk: a browser tab cannot overflow onto disk the way a native application does."}]},{"text":[{"text":"The internet connection is dropping, and Photopea reloads when it cannot reach its server."}],"correct":false,"tempting":[{"text":"Assumes server dependence that does not match the tool’s behaviour: Photopea does the editing locally in the tab and continues working through a connection loss."}]},{"text":[{"text":"The document has exceeded the browser tab’s memory allocation, which has no disk overflow, so the tab is terminated rather than slowed."}],"correct":true,"tempting":null},{"text":[{"text":"Too many layers are set to a blend mode other than Normal, forcing isolated compositing that the browser cannot handle."}],"correct":false,"tempting":[{"text":"Picks a real cost driver as the whole explanation: isolated group compositing raises memory use, but the abrupt termination is the allocation ceiling rather than any single feature."}]}],"order":[1,2,3,0],"why":null},"prev":{"slug":"setting-up-to-work-fast","title":"Eleven shortcuts and a scratch disk","minutes":8},"next":{"slug":"selections-and-edges","title":"Selections are easy until you reach hair","minutes":10}}}