How do you know it's not a computer issue? I had problems running S1 with an old Pentium D dual core running at 3.2 Ghz with only 4 GB memory. It ran like **** and I couldn't even have more than one Mai Tai going with lowest quality. Then, I found an old Dell OptiPlex 3020 in a dumpster. It has Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz 4 GB memory, Dedicated Graphics card with 1 GB, and I bought a 1TB SSD. It runs so well that I forgot to get more memory for it. There is a problem when I have Chrome open with like 8 tabs open but, that's a memory problem. I've run 3 Mai Tai and triggered 4 different instruments with 4 fingered chords at the same time and it does fine. I just ordered 16 GB memory though.
HTH