A few thoughts:

You can make sure other processes are not interfering. Run the free DPC Latency Checker, or the free Latency Monitor. The DPC site has useful instructions for how to approach the process. [For anyone else reading, DPC is better on Windows 7 only; 8 and 10 gives readings way too high].

I do remember the ability to run a program at high priority, processor-wise, but I haven't used that in Windows for over 10 years.

Are you aware of the two checkboxes in Preferences, RealTracks that are for 'slower' PCs? No harm in using them even if your machine is top of the line.

And of course, always reboot first, which clears system resources.

You mentioned the SD-50, which makes me wonder if what you are hearing (or aren't hearing) is from MIDI notes dropping out. All these MIDI synths have limits on polyphony, the number of simultaneous sounds. What people may not realize is that out of a limit of 64 or 128, a single sound is usually not one but more likely a combination of three to six sounds. Put in harmony and several MIDI tracks and you are over the limit. Check your Roland manual for your limit, and look at the patch list of sounds and you'll see what I mean. If this is happening to you, record one or two MIDI tracks to audio and take the song into RealBand or another DAW.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.