This table shows both the initial and subsequent startup times for various releases. Most of the qualifications and caveats from my AutoCAD 2009 – The Prequel Part 6 – Initial Startup Time post still apply here.
AutoCAD 2009’s subsequent startups are much less slow than its agonising first startup, as to be expected. Windows XP is doing that by caching and reusing recently used parts of memory. Release 12’s old code, running in 16-bit emulation, is not able to take advantage of that. It’s definitely an unfair test of Release 12 on this system.
In my tests, AutoCAD 2009 startups (both initial and subsequent) are about twice as slow as other recent releases. Users of older releases on modern systems can enjoy startup performance over ten times better.