Perfect free PC optimizer, good looking and you can actually choose the function where it increases the startup speed of your device.
Malwarebytes - Malwarebytes protects you against malware, ransomware, and other advanced online threats that have made antivirus obsolete and ineffective. Free Anti-Malware & Malware .
Ad-Aware Free Antivirus+ - Ad-Aware Free Antivirus+ is a world’s most leading security solution that gives you comprehensive malware protection with real-time monitoring, threats alerts and automatic updates you can rest easy knowing that you are protected.
Panda Antivirus for Mac - A bare bones malware and anti-virus scanner.
CCleaner - CCleaner cleans, speeds up and frees up space on business endpoints.
Clam Xav (desktop) - Specifically with Clam Xav Sentry configured to scan inserted disks.Please read global comments on this question for an explanation of why desktop apps are being recommended for virus detection on ios devices.
Norton PC Performance Optimization - Norton PC Performance Optimization that is also called as Norton PC Optimizer is the PC speed enhancement tool by the Norton security system.