Mac Cleaner Pro — the best memory cleaner Mac
and free RAM optimizer

macOS divides RAM into four categories that the memory cleaner mac module reads directly from the kernel. Wired memory is used by the kernel and locked — it cannot be moved or reclaimed. Active memory is currently in use by running apps — also not reclaimable without closing the app. These two categories are simply the cost of your running workload. The interesting categories for a memory optimizer are inactive and compressed. Inactive memory held pages that were active but are no longer being used — an app that is open but backgrounded, or a document that was opened and then saved. macOS keeps these pages in RAM in case the app needs them again, but will release them immediately if a new app needs the space. The memory cleaner mac flush operation releases inactive pages voluntarily, giving that RAM back to the system before a new app has to wait for it.

Compressed memory is the key concept for understanding why a Mac with 8 GB of RAM can feel slow even when it has not hit its physical limit. When inactive pages accumulate and new apps need memory, macOS compresses the inactive pages rather than writing them to disk (swapfiles), which is faster than disk I/O but still adds latency compared to accessing pages from real RAM. The compression/decompression overhead is visible as brief pauses when switching apps, sluggish browser tab restores and delayed Spotlight results. A memory cleaner mac flush decompresses and releases these pages, restoring the responsiveness that compression was hiding. The effect is most noticeable on 8 GB Macs — the M1 and M2 MacBook Air being the most common example — where the unified memory architecture amplifies both the benefits of compression and the cost of hitting its limits.

Memory pressure is the synthesised metric macOS calculates from the ratio of free-plus-inactive to total RAM. Activity Monitor shows this as the memory pressure graph — green is fine, yellow is warning, red is urgent. Mac Cleaner Pro reads the same kernel statistics Activity Monitor uses (host_statistics64) and displays pressure as a numerical score with a history graph. The optimizer triggers a flush suggestion when pressure enters the yellow zone — before apps start noticeably lagging — which is the correct time to intervene. Waiting until red pressure means the Mac is already swapping aggressively and the flush will take longer to have an effect.

The memory optimizer inside Mac Cleaner Pro performs a controlled flush: it calls the Mach kernel's memory pressure notification interface to signal that inactive and purgeable pages should be released, then monitors the pressure score for 30 seconds to confirm the flush had effect. The result is typically 1-2 GB returned to the free pool, a drop in the memory pressure score from yellow to green, and a noticeable improvement in app-switch latency within seconds. This is what the memory cleaner mac feature actually does — not a magical RAM-boosting trick, but a well-timed call to the kernel's existing memory reclamation mechanism, triggered at the right moment by an advisor that has been watching the pressure trend.