Is there any antivirus software that DOESN'T slow down Time Machine? Time Machine making a backup to my TimeCapsule has been extremely slow. 

I finally figured out that it was an issue with Avira Antivirus. So I looked for a better software. Seeing the reviews I went for Sophos which is another free software. 

What a mistake! Same problem there and some others too.

So, let's forget about free software then, I thought. Let's get the number one software (according to Tom's Hardware) Bitdefender instead! But this time I won't be so naive. I'll do my research first. And after a quick googling I find they have the same problem as the previous to contenders.

So, is there any antivirus software that won't break vital functions for my Mac?
I'm not really sure if this fits the ask different format, however, according to AV-TEST (the closest thing to an authority on the subject) BitDefender comes out very high on their scores, especially on the 'slowdown' tests.
I do use it on Windows &amp; it's a lot less irritating than some I could mention. 

Avast on the Mac is a known resource hog, btw. I could even feel it on a dual 6-core Mac Pro.
oops, Avast/Avira... they're both near the bottom of the speed tables, so I'll leave it as is