Google has confirmed that landing pages hosted on slow or unresponsive servers will be devalued. PPC Quality score, the algorithmic factor that can make or break a paid search campaign will be affected by shaky web hosting.
See AdWordsAdvisor post in major search engine optimization forums:
What do you need to do to make sure your pay per click ad campaigns? Evaluate your web hosting by using a tool to ping your server from multiple locations. Iwebtool has a good website speed test here.
Netpaths is an Adwords Certified PPC management company and we will help any business using paid search to optimize any website speed issues.