How about implementing/installing the very great "Executive" task scheduling utility into Amikit?
I registered it once in the 90s for 20DM, meanwhile it's on Aminet with free public key.https://aminet.net/search?query=executive
It can massively improve multitasking and system balancing. (It once has been stated belonging to the few best ever developed utilities for the AmigaOS).
I didn't wanted to have my original machine operating without it again (even with my DCE 060). Properly configured which may take some patience it will smoothen CPU load and keep heavy load task like creating .7z archives or else from causing lag that may occur e.g. screen switching or lets say creating more than one archive at a time or having other CPU intense tasks running.
Try it out, WINUAE will even on your rig show signs of lag when starting more than one heavy load tasks despite being set to above "normal priority".
I tested after creating two files with each 30MB in Ram to simultaneously create two individual .7z archives. You will see what happens after starting the first process.
There wasn't hardly any system/mouse response when doing this on my Amikit XE 11.4 system. I couldn't start the second archiving process and had to wait until the first archive was finished.
As expected doing this on my own AmigaOS3.9 installation (with Executive) it was no hassle at all to get both jobs done. No lag at all (at last I started 7 archiving processes simultaneously going smooth in the background). ATM. I'm in the process of rebuilding my entire Amiga data archive of ~1,4GB switching from .lzx to .7z archives.
One would say, hold on - each task would take longer than starting one by one. Yes, but it's not like double, triple or multiple the time needed. After all it's about having to wait for one task to be finished due to lag or to simply go on with whatever work the user want's to do with the system.
I set up both systems with 1GB of ram for archiving files with each 10MB in size as the 7z implementation (v9.13) can eat up several hundreds of MB ram per archive.
This part is the first paragraph from the readme file provided:
"WHAT IS IT?
Executive brings real multitasking to AmigaOS. Executive is a UNIX-like
task scheduler for Amiga. It also has plenty of other features previously
available only in larger operating systems.
Executive improves the responsiveness of your Amiga. One CPU intensive
application no longer causes the whole system to crawl. You can start
many CPU intensive applications and the system still feels as if it
would be totally idle.
The Executive package also includes many useful client programs that let
you control tasks and monitor what's going on in your system.
No similar programs for Amiga have been made before, so you may not
exactly know what Executive is all about, but give it a little time
and read the documentation and you won't regret it!
Executive is the highest rated item of shareware CU Amiga magazine has
ever awarded at 98%.