One of the most important thing, if you wish to rank high, is the download speed from your pages. This is not only limited by the bandwidth from the machine that’s hosting your site, but it’s also by the ability to accept multiple petitions at the same time and at a nice rate.
Another important point and the reason for this post is the Gzip compression feature, that obviously, would compress your files before sending them, allowing for, on the worst case, a marginal reduction of download time.
By now I know that in Spain Arsys its not supporting this on shared plans, and Dinahosting on the other hand, its offering the feature on shared plans. Both are on the same range price.