does it fix timing issues?
Yes, on the one game that had timing issues for me, I was able to adjust the speed linearly by setting the option:
[cpu]
cycles=2500
in a custom configuration file for that particular game. The adjustment is pretty smooth and linear, so that I am able to tweak the setting to be just right. 1000 was too slow, 4000 was too fast, for example. I'm still tweaking that particular game. Stellar 7, by the way, is the game. And yeah, I specifically tried both CPUKiller and MoSlo, and neither worked for this game, but DosBox did.