Virtualdub2 speed. .mov to .avi

[occasional]

I have been converting .mov files to .avi (xvid). This has been happening at a satisfactory speed and then suddenly the process has started to run ridiculously slowly (taking five or more times as long).
Can anyone suggest what might have changed ?

[jagabo]

Different frame size? Different frame rate? Different Xvid settings? Different filters? CPU overheating and throttling back?

[occasional]

Seems to have happened independently of the source video ie the same video takes much longer than it did previously. Presumably some parameter has changed but it is nothing that I have done deliberately.

[johnmeyer]

Re-read jagabo's answer above. As usual, I think he has it right. To determine if overheating is the cause, download a free utility that measures CPU temps. You want to look at the temperature on ALL of your CPU's cores.

[occasional]

I have downloaded and tested with Core Temp. There is no obvious problem, although there is only one core temp available.

[occasional]

Eventually discovered that something unidentified was pushing processor usage up to 99% and re-installed Windows etc. assuming that the unidentified was a bitcoin miner or something similar. Strangely, on the new system, an audio enchancer produced a similar problem.