I have been using 86box for a few years since I got into M1 Macs, and their support on it has been stellar since day one, thanks to coldbrewed, battler and others.
About its performance, it performs as expected. I have four machines, spanning across the 90's, an early 90's dos/w311, mid 90's win 95, late 90's win 98 and win Mistake Edition. Only the last two have voodoo 2 emulation. These four machines have different configurations for each machine I owned in such periods.
When I got into M1, I was searching for a solution that could let me play favorite games like Grand Prix 3 and FIFA 99. 86box did the job. I can play both perfectly with Parallels and Win 11 arm64, no problem, but 86box lets me play with the Win 98 atmosphere and nostalgia. And is pretty straightforward to use, mount the machine, install the operating system and games, like it was in 90's. Best I can do (in a M1) is a Pentium II 266 MHz with 128mb ram and voodoo 2 12mb. And runs very well, very well.
PCem never really had an official mac port despite some great efforts from users like kyr0 to make it run, but my games were kinda bad. Can't talk about UniPCEM either since I never really used it.
As for DOSBox-X, I did have a fair share of years using it. I feel it was a lot slower than 86box and limited. It does not run optimally GP3 and FIFA 99 as 86box can do.
Been doing such researchs since 2019, trying, testing, taking notes, and all these years paid off when I came to a solution that works for all my childhood games. They're spread between the four 86box machines, for 80's and 90's games. The 2000's games were put in Parallels Win 11 vm since they're quite more demanding. The game count goes beyond 120 games and still adding more.
@solemgar: I think you should give 86box a good chance and contact the people at their discord for more tips to improve. PCem afaik isnt being actively developed nor being developed at the same rate 86box has been in the recent years. What is your host machine configuration? So we can find a sweet spot 86box machine for you.
"Design isn't just what it looks like and feels like. Design is how it works."
READ: Right to Repair sucks and is illegal!