UPDATE FOR 6.5 USERS
For those reaching this thread looking for information about perceived latency increase between Cubase 5/6 and 6.5. - and have found the increase is due to running the Multiband Compressor;
While it’s true that later versions of the VST3 Multiband compressor do add noticeable latency when placed on the main output bus, this can easily be fixed by activating the ‘live’ mode (small button bottom right of the effect’s interface.)
I recently upgraded from Cubase 5 to 6.5 on mac and whatever i did with soundcard buffer etc there was a large latency increase when playing virtual instruments.
Through process of elimination I found that the latency wasn’t actually between my midi controller and the instruments, but was introduced at the output stage on the main stereo output bus.
I had a set of plug-ins as across my output buss as part of my default templates.
Turning off plugin one by one I found (like others) that the Multiband Compressor was the culprit.
Seems the new, more advanced ‘look ahead’ feature built into later versions of the plugin cause the latency.
After forum search found people talking about the ‘Live Mode’.
Tried clicking this button and all latency is reduced to the level I was used to in Cubase 5.