I’m in the middle of the project and everything started delaying… For example, I’d press the playback, and it has this 0.5 sec delay. If I play a note from a VST instrument, there is that same delay, and it just happened out of nowhere… I tried freezing all the VSTs to check if it’s the cpu/ram issue, and it’s not. When I open a completely new project, then that delay disappears… please help
If you disable all the tracks and create one new one is the problem still there?
Have you tried disabling all the plugins?
Have you tried backing up the file (File/Backup Project and create New Folder and copy all files)?
-Use the correct audio driver
-set useful buffer sizes
-disable plugins with high plugin delay
Right now there are no plugins other than 1 stock reverb. The delay itself is not dictated by which track but rather the project as a whole. For backing up, do you mean reloading them in a new project to remove the delay? I could do that and it’d be gone, but still I’d like to find out why …
The audio driver is right now Fireface (that’s the interface I’m using), the buffer size is 1024, that’s usually what it’s at during my tracking process… it’s been working well with this setting previously. And there are no plugins other than 1 reverb which shouldn’t affect anything really… 
Yes, but if you try what I selected it may tell you where.
I mean Backup using the commands I suggested above. This copies everything to a new folder for you automatically. It may solve the problem or it may not. Either way it will give some information as to the nature of the problem.
1024 samples is rather a lot for tracking. That alone will give you roughly 20 ms of latency at 44100 kHz project samplerate. And yes - a reverb VST can add to that. Since you don’t tell us which one that is, all you have to do is switch it off (not simply bypass).
And also any plugins in the Control room (if used) add to the total latency
The thing is with 1024, I had previously run up to 30+ instruments that are hogs, like Diva, Omnisphere and etc. and it was lag-free. Right now, there are half as many, but it’s lagging a lot. Freezing the tracks didn’t help… a reverb is Revelation, but a single plugin shouldn’t affect my computer at all…
Latency isn’ t necessarily about the number of plugins, but the Plugin delay. One plugin with high plugin delay will cause latency on any computer. Also will the buffer setting.
Are you sure you do not have a multiband compressor or limiter on the master bus.
Plugins retain their latency when bypassed, turn them off.
Well that is usually the problem, there are other possibilities like faulty drivers, vsti or a OS update.
There is good button on project window (upper and lower command bar) called Constrain Delay Compensation. Press this button and Cubase bypasses all plugins that creates latency.
Well, this doesn’t work on Ozone 8. I have an instance of Ozone 8 and Total Balance Control on my Master channel, and if I turn the metronome on, there is some significant latency there, and hitting the Constrain Delay Compensation doesn’t fix the problem, even when I change my audio buffer out to 1024 samples.
ANeeman’s explanation of how “constrain delay compensation” does work isn’t correct, so probably everything might work as it should in your case. And as written before, 1024 samples buffer introduce a relatively high latency themselves.