I don't use any type of ad blocker or other browser plug-in because the site costs money to operate and I don't want to send the owners a check for my usage
IE will always be slower because it's clunky software, ads or no ads
I use Firefox and have DSL.
I have not experienced any problems, at least not lately. There have been times in the past where there has been some sluggishness but it was not related to any ads running on the site. Instead it was high server loads generally due to an influx in site traffic.