FCPX is MUCH slower at transcoding optimized media than compressor

I'm working with some long H264 files, so I'm transcoding before editing.

If I use FCPX's native function to optimize the video it takes forever. If I transcode the exact same file to prores using compressor, it's done in no time at all... we're talking a maybe 50x difference in speed here, which seems crazy.

Any ideas what I can do to address this? Many thanks.

(Using an M1 Macbook Pro. All software is up to date.)

Just guessing, but perhaps FCP has too many plugins and maybe it’s cache and background tasks are not optimal. Compressor on the other hand has none of that to contend with.

Thanks for the reply. Both are new installs so it shouldn't be that.
FCP optimizes some stuff fine... Other stuff? Less so.
I've heard some people are having issues with FCP's handling of H264 files on the new M1 Macs - don't know if it could be this.

There is an FCP performance bug unique to Apple Silicon but it is only when creating 50% H264 proxies from 4k originals, not when creating ProRes proxies or optimized media, and not when exporting to 1080p H264.

I just tested transcoding to optimized media on a 10-core Vega 64 iMac Pro vs M1 Max MacBook Pro 16. Both were running FCP 10.6.1, Compressor 4.6 and Monterey 12.1. The test clip was 11 minutes 4k/23.98 8-bit 4:2:0 H264 XAVC-S from a Sony A7III.

iMac Pro, FCP create optimized media: 5 min 34 sec
iMac Pro, Compressor transcode to Quicktime ProRes 422: 7 min 2 sec

M1 Max: FCP create optimized media: 1 min 25 sec
M1 Max: Compressor transcode to Quicktime ProRes 422: 1 min 31 sec