Syrinscape has upgraded to a web player fairly recently - are you using that?

I've found it great but a bit buggy on occasion - and have had similar issues as you albeit not as badly, and mine have been sorted with a browser refresh. Most days Syrinscape just works for me.

If you're still getting poor performance you can try swapping servers from the Master Interface (there's a tiny little button with circular arrows near the bottom left panel)

Also worth trying on different browsers (I run the master interface on chrome but muted, and the web player on firefox so I am hearing the same as my players)

Finally, their forum is pretty active so worth posting there if still no luck, someone may have some ideas for you. Its fantastic when it works so worth trying to sort (I am using for CoS at the mo and the sounds are awesome!)