Point one is most probably caused by SpeedStep (or the AMD counterpart), which adjusts the CPU speed as needed. UT99 takes the CPU speed at startup to define the time (CPU speeds were static back in those days
and hence a change in speed will result in slower or faster gameplay. The problem is (sometimes) not easy to solve, I had to do several tricks to my CoreDuo laptop until it worked properly. Check
this thread since it's on a similar problem. We had a much nicer and more detailed thread about this issue, but it got lost in the third great forum crash
.
Also it's not like nobody plays it, it's just a rather limited ammount of people - and as far as I checked recently most of them play COOP, a gamemode where you fight against Unreal Monsters in U1/RtNP and custom map packs. Also COOP servers (usually) only shows up in the "Other INF Games" tab of the ingame browser.