Bitdefender Does It Slow The Pc Speed?

Hello everyone.I'm currently using avast free but i heard that avast isn't that good for protecting from malware,trojan etc.Yes,it detects and removes the malwares but it may leave some dropped malicious files and changes so i want to buy a better av program.Normally i would decide in kaspersky but i heard that it slows down the pc so i decided to buy bitdefender.What i wonder is does it slow down the pc?and i also read that some avs slows down the internet speed especially the page opening times.Does bitdefender do anything like this?If it doesn't have problems like this i'll buy it immediately.
Also do you guys prefer ks or bd.or if you know better av program which has good protection and doesn't slow down the pc and internet you can write it too.
Thanks everybody for the answers.

I have been a devout user of ESET Nod32 for years mainly due to its extremely low footprint and decent protection. However, one of my computers got infected with a lot of viruses that ESET wasn't detecting so I installed Bitdefender and cleared them up, and Bitdefender has one of the very best antivirus systems.

After that, I also installed Bitdefender on my main laptop, which is pretty decent i5 CPU, 2GB RAM, etc. Even though I turned off all the extra features and just left the antivirus and firewall, I started having slow programs and laggy usage on both computers soon after. Most noticeable issues are when switching between programs when several are open, always freezes my computer for a while.

Even when I check CPU usage and Bitdefender is not using anything, it is still laggy.

I can't PROVE it's due to Bitdefender but I never had problems before and I'm going back to ESET Nod32 as soon as possible, despise the lesser protection,.

I'm in the midst of testing antivirus solutions for work and have so far trialled bitdefender cloud, sophos and vipre.

bitdefender was easy to deploy but brought my machine to a crawl when running a scan - i7 860 with 8GB RAM running win7x64

sophos was good and the business management console has a lot of functionality - pc showed some signs of slowing during a scan but was still usuable

vipre was easy to install using their management console and even running a deep scan on an old dual core pentium, you would have hardly known it was running. As well as being more affordable this is the best I've tested so far.

Sutra

I have checked it , it is slowing down the performance

How have you checked?

All antivirus programs will slow your computer.

I was using many antivirus softwares like kaspersky,AVG,Avast, I am craze on different antivirus so tried comodo AV and liked it lot used it for 2 years ...