Okay, here's where to look in Cubase (assuming, of course, that your sound card looks the same as mine in this part of Cubase)...
Follow the pull-down menus until you get to:
Devices ---> Device Setup ---> VST Audiobay
Once you get there, you should see a box with a little pull-down arrow with the name of an audio driver in it. To the right it should say "Master ASIO Driver."
Underneath that, it should say
Total Input Latency: __.___ms
Total Output Latency: __.___ms
With my MOTU, I have three options, which I can access by clicking on that little down-arrow...
"DirectX ASIO" (which gave me readings of 46.440ms in each direction);Obviously, you should start by selecting the driver that gives you the lowest latency numbers.
"ASIO Multimedia Driver" (110.00 Input, 749.932 Output), and
"MOTU PCI ASIO" (a relatively mangeable 12.109ms in each direction).
Then you should see a button marked "Expert..." below all that.
When I click that button (and, hopefully, when you do too), there are two drop-down boxes and three check boxes.
My drop-down boxes read as follows:
"Audio Priority" = "Very High"
"Preload Amount" = "6 Seconds"
You can try different settings to see if anything helps.
I have all three check boxes checked:
"Lower Latency," "Multi Processing" and "Adjust for Record Latency."
I'm guessing that the middle box should only be checked if you are running a dual-core or dual-processor machine (mine is dual-core, so I have it checked). I'd suggest trying to check both of the other boxes if they aren't checked already.
You may have tried all this already... Hope that this is even the tiniest bit helpful...