For some reason I just can't get that many effects to work in my songs in openmpt, and when it comes to vst instruments i mostly use Synth1. In fact pretty much all of my openmpt songs that have vst use synth1 and/or odsay and i generally barely use any effects at all, unlike in LMMS where i have more control over LADSPA and vst effects.
Well I am doing it in 32bit ompt, since all my vsts are 32bit... maybe we on the forums here can give you some advice, or maybe I can... tell us what version of ompt you are using, your OS, the specs of your rig, and your soundcard settings in ompt...
For example, I am on a laptop, windows 8 64bit, 16 gig ram, intel core i7-5500u 2.4GHz 2.4GHz
on OMPT 32bit latest stable release
wasapi, default, latency : 2ms, period : 5ms, Format 48000Hz Stereo
with boost thread priority on.
This is a few years old laptop, so you very likely have a better machine than me, so maybe it would help to match my OMPT settings and see what you get.
But if you have a worse machine, then I can say one trick that works even for my XP laptop (much much older than this) is to work on a lower Format - for example on that one I tend to up the latency and period (often as far as it will go) and take the format to 22050Hz (you can always set this higher for export, but I often didnt, because I prefer to hear what I am going to export, and 22050 actually sounds pretty good in my opinion) and yeah I had loads of vsts working on that XP laptop at once, and some 32 bit vsts I just cant get working on modern systems unfortunately.
