Screen protector question

I've just fitted a screen protector to my iPad, as I typically have always done with all of my touch screen devices. I generally have always bought cheap ones off eBay, and have never had any problems, however my iPad now feels less responsive.

1. Am I imagining this- does a screen protector affect screen responsiveness?

2. How big a difference is there between the £2 protector that I bought, and the £10 one that apple sells?

Thanks in advance