Aphera decodes RAW files and keeps the results in caches so that browsing and editing don’t wait on the same work twice. The Performance pane sets how much of your Mac those caches and that processing may use.

Open it from Aphera > Settings (Cmd+,) and select Performance. Every setting applies to the app, not to a single project, and takes effect as soon as you release the slider.

Slider ranges are derived from the hardware Aphera is running on: installed RAM for processing and memory, volume capacity for disk. A setting brought over from another Mac is clamped to what this one can support.

Processing

Max N images at a time sets how many images Aphera may decode at once. Higher is faster, but each image in flight holds a full-resolution buffer, so peak memory rises with the setting. The right number depends on the CPU, the amount of RAM, and the megapixel count of your RAW files.

  • Default: one image per 8 GB of installed RAM, never fewer than 1 and never more than 12.
  • Range: 1 up to a quarter of installed RAM in GB, never less than 4 and never more than 16.

Setting it to 1 is a real choice, not a broken one — imports take longer but never push the Mac into swapping.

Below the slider is a live readout: Processing is idle, Currently processing N images, or Currently processing N images, with M images waiting.

Grid rendering takes priority over background work such as importing, so scrolling stays responsive while a large import runs.

In-Memory Cache

The amount of RAM used to hold image previews. More images in memory means less re-rendering while browsing and editing.

  • Default: a quarter of installed RAM, between 2 GB and 16 GB.
  • Range: 1 GB up to half of installed RAM, capped at 32 GB.
  • Adjusts in steps of 1 GB.

The footer shows current usage and a Clear button that empties the memory caches immediately.

On-Disk Cache

The space used for RAW proxy files. Proxies are generated once and reused, so a larger cache means less waiting when reopening a project.

  • Default: a tenth of the capacity of the volume holding the cache, between 5 GB and 50 GB.
  • Range: 5 GB up to a fifth of that volume’s capacity, capped at 100 GB.
  • Adjusts in steps of 5 GB.

The footer shows current usage and a Clear button. Clearing asks for confirmation (“Empty the disk cache?”); confirm with Empty Cache. Aphera re-creates proxy files as needed afterward, which slows down browsing and editing until it catches up.

Statistics

Readouts for judging the settings above:

  • Active memory — the memory Aphera is using now.
  • Maximum memory this launch — the highest figure reached since the app started.

Both update while the pane is open. To size the Processing slider, watch the maximum during an import: if it approaches the point where the Mac starts swapping, lower the setting.

Reset to Defaults returns the sliders to the values derived from this Mac’s hardware.