In general; yes. Most anti-virus programs do on-demand scanning, meaning they check all files as they are being requested by various programs. This real time scanning requires drive access, processing and some memory, all of which contribute to a slower machine with less battery life.
However, I'd heavily advice against the use of anti-virus programs on Macs. Anti-virus programs for Mac usually don't have any Mac virus signatures that they check for. The main point of these programs is to check for Windows viruses, and prevent accidental infection of coworkers'/family/friends' Windows PCs. Mac anti-virus programs tend to be scams, which although may offer legitimate detection of Windows virus, are simply meant to pray on users and push them into purchasing a paid product.
Apple does a GREAT job at patching up various vulnerabilities, so you should rest assured that your machine is very secure, as you're likely not a high profile enough personality to be worth the effort to hack.