i think the "snappiest" thing you can do is disable frames in images while loading, it at least tricks your eyes. here's the stuff you can put in your user.js for optimal snap. it's from a sticky on mozillazine, so it's not witchcraft/nonsense.

user_pref("browser.cache.memory.capacity", 65536);
user_pref("browser.cache.disk_cache_ssl", true);
user_pref("browser.xul.error_pages.enabled", true);
user_pref("content.interrupt.parsing", true);
user_pref("content.max.tokenizing.time", 3000000);
user_pref("content.maxtextrun", 8191);
user_pref("content.notify.backoffcount", 5);
user_pref("content.notify.interval", 750000);
user_pref("content.notify.ontimer", true);
user_pref("content.switch.threshold", 750000);
user_pref("network.http.max-connections", 32);
user_pref("network.http.max-connections-per-server", 8);
user_pref("network.http.max-persistent-connections-per-proxy", 8);
user_pref("network.http.max-persistent-connections-per-server", 4);
user_pref("network.http.pipelining", true);
user_pref("network.http.pipelining.maxrequests", 8);
user_pref("network.http.proxy.pipelining", true);
user_pref("nglayout.initialpaint.delay", 750);
user_pref("plugin.expose_full_path", true);
user_pref("signed.applets.codebase_principal_support", true);