Sorry, Hood can you be more specific about the time in Int? This may help others as well.
The Time in Int can be seen on the Diagnostics page and what it is is the time that Mach needs to do its pulsing properly.
The Time in Int will not vary much at all on a computer with different kernel frequencies as it is computer specific and not kernel dependant.
Where the problem comes is different kernels produce a different interrupt time and if the time in int (time in interrupt) is high then it means there is less time for the computer to do all the other things it needs to do other than the actual pulsing.
So say your time in int is 10 then at 25KHz kernel there is 30uS left for the computer to do its thing (1second/25,000 = 0.000040Seconds or 40uS. 40uS-10uS = 30uS) So your computer is 25% pulsing engine 75% everything else.
At 45KHz kernel the interrupt is now down to 22uS so with the Time in Int being 10 in the above example there is only 12uS for the computer as the pulsing engine is taking almost 50% of the interrupt.
At 100KHz it would be even worse, in fact it would be critical as there would be no time at all for anything other than pulsing and your computer would be totally locked up.
So as you can see there is a good reason not to have the kernel higher than you need and even if you do need it high it may not be possible on that particular computer. 10 is quite a high value for the Time in Int and yours may be a lot lower, this computer I am typing on is about 3, if I recall, so even at 100KHz it is still only 33% pulsing engine and 77% left for the rest of the computers functions, which includes everything else Mach does apart from the actual pulsing and also everything else Windows itself does.
Hood