FluffyBench

Can a browser convert a 10,000-file photo batch?

Yes—a browser can work through thousands of photo files by handling a few at a time. Here’s how that queue works and what to check before trying your own collection.

FluffyBench · 7 min read · Reviewed

How can a browser handle thousands of photos?

Think of a checkout line: a few photos are being served while the rest wait their turn. With a live ZIP download, finished copies leave the work area as new photos move in.

Waiting photos feed a few active conversions; finished copies enter the ZIP and free room for more work.

A long queue, a small work area

  1. Waiting

    Selecting a file doesn't mean keeping its full picture open in memory.

  2. Working

    Batch speed sets the limit on simultaneous conversions. FluffyBench Image Space Saver can lower that limit for pictures that need more memory.

  3. Finished

    The ZIP receives each completed copy as the queue moves along.

The length of the queue and the amount of active work are different things. How we reviewed

What happened when FluffyBench processed 10,000 files?

On 2026-10-11, FluffyBench Image Space Saver reported 10,000 completed files and 0 failures: about 20 minutes converting to WebP, or 22 minutes including file checks. Resizing was off, so the job kept the original pixel dimensions.

Reported run: about 2 minutes of checks, then 20 minutes of conversion; 10,000 done and 0 failed.

The completed run, from its report

2026-10-11 · Chrome 155.0.8059.39 · historical Image Space Saver build. The list used 83 generated source images repeated across 10,000 files.

Memory in use peaked at 3.1 GiB across the browser's processes. That's the useful result for a big collection: the queue kept moving without holding every full-size picture open together.

Need to convert a photo collection in the browser?

Doing it in FluffyBench

FluffyBench Image Space Saver handles the queue and can download finished copies into one ZIP as it runs. Your images stay on your device. Here's a first batch you can inspect before committing a whole collection to the same settings.

These current-workspace screenshots use two JPG copies of a flower photo. Start with file selection and the output settings.

  1. Image Space Saver intake with Choose images.
    Image Space Saver intake with Choose images.
    Step 1. Choose files that include your collection's formats. Keep the originals.
    1. Choose images opens your file picker.
  2. FluffyShield workspace toolbar with the settings gear beside the Auto Balanced and Universal summary.
    FluffyShield workspace toolbar with the settings gear beside the Auto Balanced and Universal summary.
    Step 2. Open Settings with the gear above the workspace.
    1. The gear opens Settings; the text beside it names the current profile.
  3. Profile with Custom selected.
    Profile with Custom selected.
    Step 3. Choose Profile: Custom.
    1. Custom exposes Format and Maximum quality.
  4. Format set to WebP.
    Format set to WebP.
    Step 4. Set Format to WebP.
    1. WebP is the format used in the historical run.
  5. Maximum quality set to 80.
    Maximum quality set to 80.
    Step 5. Set Maximum quality to 80.
    1. 80 is the quality this guide's run used.

Size, Batch speed and the ZIP option finish the setup. The historical run used Fast; this first batch uses Automatic.

  1. Size set to Original.
    Size set to Original.
    Step 1. Keep Size at Original.
    1. Original keeps the pixel dimensions.
  2. Batch speed set to Automatic.
    Batch speed set to Automatic.
    Step 2. Leave Batch speed at Automatic for your first batch.
    1. Fast can start more work at once and uses more memory.
  3. Download as one ZIP as it runs is checked.
    Download as one ZIP as it runs is checked.
    Step 3. Turn on Download as one ZIP as it runs.
    1. Finished copies enter the ZIP as they finish.
  4. Process 2 images button for the demonstration files.
    Process 2 images button for the demonstration files.
    Step 4. Press the Settings gear again to close the panel, then Process 2 images. Keep the page open until the ZIP finishes.
    1. The Process button includes your selected file count.

What should you check in the finished ZIP?

Here's the completed demonstration batch, its downloaded ZIP contents and a WebP opened from that ZIP. The archive listing comes from the actual download; this is a separate illustration from the historical run.

  1. Completed Image Space Saver batch with Done 2, Needs a look 0 and two In ZIP results.
    Completed Image Space Saver batch with Done 2, Needs a look 0 and two In ZIP results.
    Step 1. Match Done to your selected count. Review Needs a look when it has files; In ZIP marks copies passed to the download.
    1. Both converted copies reached the ZIP.
  2. Actual listing of the downloaded illustrative ZIP: two WebP files with their dimensions and sizes.
    Actual listing of the downloaded illustrative ZIP: two WebP files with their dimensions and sizes.
    Step 2. Wait for your browser's download to finish, then open the saved ZIP. This listing was read from the downloaded example.
    1. Check the ZIP contains your converted files.
  3. The flower WebP opened from the downloaded ZIP.
    The flower WebP opened from the downloaded ZIP.
    Step 3. Open a converted photo where you'll use it. Check its dimensions and appearance before converting the rest of your collection.
    1. Inspect the opened copy, including fine detail.

For a detail check, compare the same patch of your original and converted photo. Here are the flower's petal markings in a separate illustrative WebP conversion at quality 80, with its pixel dimensions unchanged.

The flower photograph with a box around the petal detail shown below.

Original JPG

Speckled lily petal in the source JPG.

38.8 KB

WebP, quality 80

The same petal after the illustrative WebP conversion.

11.7 KB

Rendered for illustration.

Check edges and fine texture at matching scale; the file sizes describe the complete photos. · Photo: Rosendahl; illustration assets made by FluffyBench, Public domain, released by the author, via Wikimedia Commons and FluffyBench.

An Image Space Saver result marked Kept original still has its original format. Its card explains why.

What can interrupt a large photo batch?

Fast can start more conversions at once, so more work competes for memory. A queue limits new work; it can't immediately stop a conversion the browser has already begun.

Photo icons outside a capped encoder door; a running photo inside, beside a memory arrow crossing a dashed limit.

A limit on starting work

  1. Waiting

    FluffyBench Image Space Saver decides which waiting photo starts next.

  2. Already running

    The image encoder is the browser code writing a new file. That work can keep using memory after the queue stops new starts.

  3. Not enough room

    A tab that closes during processing loses the run, including a ZIP download in progress.

The queue controls the next start; an active conversion can still run out of room.

Photo formats can leave gaps too. In the October 9 observations, Chrome left out HEIF sequence files (several pictures packed into one file), while an automated Firefox build left out HEIC photos, a common iPhone format.

Historical Chrome: 9,938 finished and 62 HEIF sequences omitted. Automated Firefox: 9,500 finished and 500 HEIC files omitted.

Which formats were left out?

2026-10-09 · Chrome 155.0.8059.39 and automated Firefox 155.0, on different historical app builds. FluffyBench Image Space Saver and FluffyBench's image converter finished the same count within each browser; these are observations from those builds.
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