With any VPN, it can, but the difference is often unnoticeable. Furthermore, if your ISP is throttling certain types of traffic, using a VPN could boost your speed. At Watch-UK-TV-Abroad VPN we run a premium high-speed network using bandwidth from tier-1 providers.
Keep in mind that your local internet speed can be several times faster than your UK internet speed. To get fair UK internet speed analysis, test your speed against UK-based speed-test server with your favourite speed-test tool or use the speed-test on our VPN Pest page HERE >>>.