If you're loading all TCZs at boot, that will slow things down initially but it'll all be cached in RAM. If you have the TCZs in the tce/ directory, it'll lessen your initial payload and reduce speed later until cached.
Loading from CD/DVD in BIOS is rather slow. USB, HDD or HTTP-enabled PXE is more often faster. A minimal boot loader load with loading additional payload to RAM after booting would likely be faster (there's a script you can do but can't recall the name, designed just for your own customization).
Where are your extensions, HDD, USB, CD/DVD? Are they loaded into RAM? If so, from the boot loader or afterwards?