Hi folks ! I have the following issue on cubase 5, and now 6 :
when i insert multiple instances of vstis, i get a midi latency problem. The midi i play on my keyboard is recorded with a delay… I’ve tried to check the “use the internal midi clock” (not sure of the translation, i’m french) in the midi preferences panel, but it don 't change nothing. My config : xpsp3, 4 gig, 60 gig ssd on c, q6600 intel quad core, asus p5qse motherboard. Any idea ? 
Bump ! Any idea ?
By “use the internal midi clock” I assume you mean System TimeStamp? And which VST’s are we talking about?
When you click to the notes in the piano roll view do they play without delay?
Yessssssssssss finally, I’m not going crazy !!! it took me ages to figure out what was doing this… I can confirm!
Multiple VST’s effects OR VSTi’s cause my midi to delay and can’t even compensate the delay… its like and out of wack delay… Last night i tried this I had a mastering chain on my output of about 5-6 plugins, played my Slyenth1 instrument through it and all your midi is out of wack, even when your just playing back the recorded midi in the project… its not lining, the sounds are missing the midi targets during play back… is anyone else experiencing this?
I have checked everything this happens on a friend of mine’s machine too… so I can confirm the bug is real.
Ohh and just to confirm I have things like
on the master
APEQ
PSP MasterCOmp
Realverb
PSP Xeon
Precision Limiter
And just one channel playing Sylenth1 on the master… switch them all off, and the problem goes away.
Anyone else?
Hey,
I see you have 2 compressors in your signal chain (compressor and limiter)…a lot of compressors add latency…(and not a little bit)…That is not because they are “bad” but because of their “look - ahaid” functions…
Hth,
Hugo
And why would you want to use two limiters? 
, (PSP Xenon & Precision) so in effect you have 3 compressors running over your master bus…(A heavilly clipped mp3, (your final medium)…is the result of an over compressed Wav, after conversion to mp3…(every second track i get from beatport has 1000’s of clips…the result of over compression…( also no dynamics, which again,will not be noticed as much at low volume, but horse it through a decent rig,and …well, the tracks just loud!,and one that many decent earred Dj’s will avoid.
If your track in Wav format looks look it has had a ‘haircut’ then that haircut will be turned into "Skinhead’ the time any Lame mp3 conversion is applied… 
also If your producing electronica (house /trance etc) DO NOT USE A REVERB ON THE MASTER BUS ( a tadge of reverb on the master is maybe ok with some pop & rock…but you wont be properly monitoring at very high SPls in your production environment ( bedroom & excuse me if I am being presumptious here that you produce at low levels) but electronica is going to be played back at very high volume levels 110 db & above, where you WILL hear reverb badly applied on the Master bus. I dont think you want your tracks to sound as if they were made in a garage as thats what reverb on your whole mix will sound like, you wont notice it as bad at low levels, but it sticks out a mile on a Funktion One.
Use reverb at the send level on your individual parts, & not on your Master bus, its bad practice, and use it only as an insert if you have a wet/dry mix knob.
As for the time sync problems,why dont you bypass the plugs in one by one to see which one is introducing latency…3 x compression and 2 limiters…mmmm…Use the Xenon coupled with any dithering if needed as your final plug…and use a frequency/level meter just before the limiter to see exactly what is being done/needed to your track. try & aim for about -12db rms, use a multiband compressor threshold & ratio to achieve the loudness you need, rather than the limiter squashing your hard earned work. 
sorry for the late reply, I loaded the VST’s on the BUSS as a test I surely would NEVER ever mix through that !! hahaha
it was a test to see which plugins were causing me problems, but in any case issue has been fixed with some latest updates and I’m now running 64bit not 32 ta.