Latency When Recording

When I start working in Renoise (recording from my USB microphone samson q1u) the latency is fine, but after some time it increases out of the blue to about a second or two. I have to restart the application and the everything is back to normal. What’s going on? Other applications do not experience increased latency at the same time so it’s something within renoise. I’m not using ASIO, haven’t decided to buy renoise yet but I don’t think it explains the phenomenon why everything is working fine (with just a small latency you’d expect) and then suddenly…

BTW i think i’m still a newbie so be patient please.