Your question is somewhat ambiguous. "Too many requests" could mean that your website's design is pulling in a lot of resources and this, particularly with Javascript, can cause load speed issues. If it is related to this you can look to merging some of your Javascript files, loading Javascript asynchronously where advisable, look at reducing CSS bloat (stripping unused rules, etc).
"Too many requests" could also mean that the server is suffering under load. If it is this latter meaning reducing any design-related resource loading issues may actually help somewhat but the site will still not reach reasonable speeds. To resolve this you'll need to look at reducing load on the server. This can be accomplished by making use of caches where appropriate.
Use the PageSpeed extension in Chrome or Firefox to diagnose some of the problems that might be affecting your site. If you suspect server load and if you have SSH access assuming it is a *nix machine try the "uptime" utility and have a look at the load averages.