I was around 601 up-votes for the ASP.NET tag today, then I noticed the Profile page changed and I am now at 582? Did something happen today?
The totals for tags are cached for a while on the database side since that's a fairly expensive thing to compute on the SO scale. Currently they're computed once a day, so the totals may be up to 24 hours old. The drop you're seeing now is just because we switched to the new data source between daily recalcs, you'll see the higher numbers return when the recalc runs tonight.
We're going to keep an eye on this (and all other performance areas in the new profile), we may up how often the tags are recalculated quite a bit since it's a common cache for all profiles, so the cost of the large calc still easily saves compared to calculating per profile on the fly.