[TECK]

Originally Posted by Boofo

But it shouldn't be going into negative numbers should it?

Yes, it should go into negative values Bobby, because we only count the query execution time.
Once we have that specific value, we deduct from it the script start time, in order to obtain the the PHP execution time.

Let's don't count the DB connection time, first. In init.php, find this line:

$db->mstimer_stop();

Replace it with:

$db->mstimer_stop(false);

Then let me know if the time is also erratic. The code mod will not add anymore how long it takes to do the DB connection to the total SQL/query execution time. I belive the time will still be erratic, only smaller values will be processed for SQL.
One more time, vBMicroStats reads ONLY what is happening behind the script, it does not affect in anyway the vBulletin functionment.

Make me a favor. Disable vBMicroStats (code, etc.), enable the debug mode and look at the explained pages, while refreshing the page several times, the same way you do now with vBMicroStats enabled.

Post the results here. On my forums, they are almost identical in both cases.
However, we need to find out why we get SQL spikes once in a while.
With SQL is simple, you cannot have SOMETIMES certain results. Is either NEVER or ALL THE TIME.