There can be various reasons that may cause you PC working slower than usual. But if it happens after installing and using McAfee then you must check for the internal space that your PC is left with. If it is showing up a red mark then you should empty the space first. Another reason behind this issue can be the automatic scans. Automatic scan may cause your system to retort slowly as it involves the functioning of two heavy applications. You have to manually schedule the time of the auto scan or disable it completely. If the situation still encountered, then you must talk to the determined technical team at 0808-101-2159 McAfee Helpline Number UK for instant support.