If OBS's memory footprint climbs noticeably the moment you start a recording or stream, and stays elevated or keeps growing throughout a long session, that's a documented pattern other users have described in detail on OBS's own support channels.
Why real-time capture is inherently memory-intensive
Recording your screen means OBS is continuously capturing frames, applying any configured filters or overlays, encoding the result into a compressed video format, and either writing it to disk or streaming it out, all in real time and all simultaneously. Each of those stages needs buffer memory to hold frames as they move through the pipeline, and the resolution and frame rate you're capturing at directly scales how much memory each buffer requires. Capturing at 4K and 60 frames per second is a categorically heavier task than 1080p at 30 frames per second, in the same way editing 4K footage in Premiere Pro is heavier than editing 1080p.
What the forum reports specifically describe
OBS's own forums have threads titled around "Excessive Use of RAM on Mac OSX" and reports of OBS "taking up most of my computer memory... while streaming," both describing memory use disproportionate to what the streaming setup itself would suggest, alongside dropped frames, which is the visible symptom viewers or your recording actually experience when the encoding pipeline can't keep up. Dropped frames specifically point toward the system being unable to process incoming frames fast enough, which can be a memory-pressure symptom as much as a raw CPU one, since a Mac under memory pressure has less room to buffer frames smoothly during brief processing spikes.
Settings that genuinely help
Lower your recording resolution and frame rate if your source doesn't need to be at maximum. Recording at 1080p 30fps instead of 4K 60fps dramatically reduces the memory and CPU load of the entire capture pipeline, and for most everyday screen recordings (tutorials, gameplay clips, presentations) the difference in final quality is much less noticeable than the difference in system load.
Check your encoder settings. OBS lets you choose between software encoding (using your CPU) and hardware encoding (using dedicated hardware on your Mac's chip). Hardware encoding is generally lighter on overall system resources, including indirectly on memory pressure, since it offloads the heaviest part of the work to dedicated silicon rather than your CPU cores.
Reduce the number of active sources and scenes. Each camera feed, window capture, or browser source you have configured, even ones not currently visible in your active scene, can carry its own memory overhead. Removing sources you're not actually using in your current setup is a straightforward way to reduce OBS's baseline footprint.
Close other demanding apps while recording or streaming. Since OBS is competing with everything else running on your Mac for the same memory pool, quitting apps you don't need open during a recording session (video editors, other heavy creative tools) gives OBS more consistent headroom, which reduces dropped-frame risk.
Watch your buffer and replay buffer settings. OBS's replay buffer, which keeps a rolling window of recent footage in memory so you can save an instant replay after something happens, holds that entire window in RAM for as long as it's enabled. A longer replay buffer window directly means more memory held in reserve continuously, even when you never end up saving a clip. If you don't use the replay buffer feature, turning it off removes that reserved memory entirely, and if you do use it, keeping the window as short as your workflow allows (many streamers only need 30 to 60 seconds) limits how much it costs you.
Update OBS itself regularly. Each new OBS release tends to include memory-management and encoder-efficiency improvements as the project's contributors continue optimizing the capture and encoding pipeline, so running an older version can mean carrying inefficiencies that have already been fixed upstream. Checking for updates before an important recording or stream session is a low-effort way to rule out a known, already-solved issue.
How this compares to a "quiet" recording task
It's worth being clear that a simple screen recording, say a short walkthrough with no filters, no multiple sources, and modest resolution, genuinely shouldn't strain your Mac's memory the way a full multi-source live stream with overlays, alerts, and a chat widget will. If you're seeing heavy memory pressure from what should be a simple recording task, that's a stronger signal something in your specific setup, rather than OBS itself, deserves a closer look, whether that's a stray high-resolution source left active, a plugin running in the background, or simply too many other demanding apps competing for the same memory at once.
Where a memory-relief tool fits in
OBS's own memory use during active capture is legitimate, ongoing work that a general tool shouldn't interfere with while a recording or stream is live. Where Shiny is genuinely useful is beforehand: freeing up memory that's accumulated from earlier in your day, closing orphaned helper processes from apps you've since quit, gives OBS more available headroom from the moment you hit record, which reduces the chance of memory pressure contributing to dropped frames during your session.
For a related demanding real-time task, see Zoom high CPU on Mac during calls, which covers a similar live-processing memory and CPU pattern in a different context.