Is Malwarebytes a Reliable program? And Still slow internet?

[ElliotDerCurious]

I've been sent the program Malwarebytes and was curious as to whether it was reliable or not. It seems to do a good job of catching malware and such and getting rid of them, but if I don't have viruses, what could be making my internet so slow? It actually freezes up and needs to be restarted if I have more than one internet related window up.