Understanding Memory Limits

T-Sketch runs inside a browser tab, and every browser tab has a fixed amount of memory it can use. That limit depends on your device, operating system, and browser. When a sketch uses too much memory, the browser may close the tab or the canvas may stop rendering. This article explains why that happens, how to spot it early, and what to do about it.

Why Memory Matters for a Drawing App

Most web pages use very little memory — a few dozen megabytes at most. A drawing app is different. It needs memory for:

  • Rendered tiles — the canvas is divided into tiles that are pre-rendered for smooth panning and zooming.
  • Stroke data — every ink and brush stroke is stored as geometry so it can be re-rendered when you scroll back to it.
  • Images and textures — uploaded images, symbols, and text blocks are stored as GPU textures.
  • Rendering engine — the engine that draws everything to the screen needs its own working memory.

A large sketch with hundreds of objects, many images, and complex brush strokes can approach the browser's memory limit, especially on devices with less RAM.

Device Memory Limits

The amount of memory available to a browser tab varies significantly across devices:

iPad and iPhone (Safari)

Safari on iOS and iPadOS is the most constrained environment. Safari will terminate a tab that uses roughly 1–1.4 GB of memory, so T-Sketch sets an effective budget of about 500 MB on these devices. In addition to the browser tab memory limit, iPads also have limited GPU video memory. The rendering engine has its own GPU memory constraints that are separate from the tab limit — if the GPU runs out of memory, the canvas may go black or show artifacts even when the tab itself has not crashed. T-Sketch automatically uses lower GPU memory caps on mobile devices to minimize this risk. Large sketches are most likely to hit memory limits on iPad.

Laptops and Desktops (Chrome, Edge, Firefox)

Desktop browsers typically allow 1–2.5 GB per tab, depending on how much RAM your computer has. A machine with 8 GB of RAM will have a lower per-tab limit than one with 32 GB.

Desktop Apps (macOS, Windows)

The T-Sketch desktop apps for macOS and Windows run in a dedicated process with a much higher memory ceiling — up to 4 GB on a machine with 8 GB of RAM. If you regularly work with very large sketches, the desktop app is the best option.

The Memory Management dialog shows your detected device and the auto-calculated budget so you always know what your limit is.

Symptoms of Running Out of Memory

Memory problems can show up in several ways. Here is what to look for:

  • The tab crashes or goes blank. The browser terminates the tab entirely. On Chrome, you may see an “Aw, Snap!” page. On Safari, the tab reloads automatically.
  • A “Memory limit reached” notification appears. T-Sketch detected that the rendering engine had to restart due to memory pressure. The notification shows a breakdown of memory usage across different areas (browser memory, GPU, and internal engine), which helps identify what caused the issue. Your work is saved, but you should reload the page.
  • The canvas turns black or shows visual glitches. The GPU ran out of memory and the rendering engine restarted. Objects may appear missing or distorted until you reload.
  • A colored badge appears in the bottom-right corner. This is the memory pressure indicator. An amber badge means usage has passed 75% of the budget. A red badge means usage has passed 90% and the app is actively reducing quality to stay within limits.

How to Check Current Memory Usage

  1. Click the ? button in the bottom-right corner of the canvas.
  2. Select Memory Management.
  3. The dialog shows your current memory usage, a per-category breakdown, and the pressure level (Normal, Warning, or Critical).

If the colored pressure badge is already visible in the bottom-right corner, you can click it to open the dialog directly.

The dialog refreshes every second while open, so you can watch memory usage change in real time as you add or remove objects.

Troubleshooting

If you are experiencing memory issues, try these steps in order — from quickest to most impactful:

1. Close Other Browser Tabs

Every open tab competes for the same device memory. Closing tabs you are not using frees up memory for T-Sketch.

2. Reload the Page

Click the Reload button in the Memory Management dialog (or simply refresh the browser tab). This releases all memory and starts fresh. Your work is saved automatically before the reload.

3. Lower the Rendering Quality

In the Memory Management dialog, switch the rendering quality from Auto to a lower fixed tier. This reduces the size of cached tiles, which is typically the largest memory consumer. The canvas will look slightly less sharp when zoomed in, but will use significantly less memory.

4. Lower the Memory Budget

If the auto-detected budget seems too high for your device, set a lower fixed budget in the Memory Management dialog. A lower budget triggers quality reduction earlier, which prevents the app from approaching the browser's hard limit.

5. Reduce Sketch Complexity

Large images, many raster brush strokes, and hundreds of objects all consume significant memory. Consider:

  • Resizing or removing very large images that you no longer need at full resolution.
  • Splitting a very large project across multiple sketches instead of putting everything on one canvas.
  • Using fewer raster (textured) brushes in favor of ink brushes, which use less memory per stroke.

6. Use the Desktop App

The T-Sketch desktop apps for macOS and Windows have significantly higher memory limits than browser tabs. If you regularly work with large sketches, the desktop app is the best way to avoid memory issues.

When to Contact Support

If memory problems persist after trying the steps above, please contact us and include:

  • Your device and browser (e.g., “iPad Pro 12.9, Safari” or “Windows 11, Chrome 146”).
  • A screenshot of the Memory Management dialog showing the category breakdown.
  • A rough description of the sketch (how many objects, whether it includes large images, etc.).

This information helps us diagnose whether the issue is device-specific or related to a particular type of content.

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