Opus 10.5.7 is 8 years old, so something else on the system must have changed for things to slow down recently.
It's probably a shell extension some other software has installed.
The Crash, exit or high CPU when viewing certain directories FAQ has suggestions on things to look for.
We could look at process snapshots if you were seeing this with a current version, but we don't keep symbols for versions more than a few years old (they use up a lot of space), so it wouldn't be possible with Opus 10.