You should also cut rendering times by putting javascript to footer if possible. CSS too if possible, but javascript has usually bigger impact.
You can also speed up load time by using more parallel downloads for objects those are not important for SEO; like banners, etc. You can increase the number of parallel downloads by putting the files to subdomain, etc (different domain). I have done it with subdomain. The parallel download limit is per domain and increasing the number of domains you can get more parallel downloads. I have seen some tests those have had best results with multiple domains, but I have seen best impact with just one additional (sub)domain.
For example if your regular file path is:
Example Domain, when you put some files into
www.pics.example.com]400 - Bad Request you can get those files to download parallel with the files from your main site.