On Win7 x86, I've noticed that vs.exe will spike the CPU briefly on launch and then go to ~0%. But as time goes on the CPU usage slowly climbs. Maybe it has to do with commands I've invoked, I don't know. But after a while it consumes as much as 25% of one CPU while completely idle.
I captured two profiles in v17.0.1 while the problem was occurring (attached). One profile with symbol coloring on, and one profile with symbol coloring off (to see if symbol coloring made a difference, but it didn't seem to).
In case it's hard to tell the overall duration from a .tsv file, each profile covered a period of around 10 seconds, give or take a little.