Whats to say? lots of things fixed, lots of speed gained

Here is the readme:
NeoDC version 2.3 for the Dreamcast by Quzar

Changes in version 2.3:
*Dreamcast specific

-No longer uses SDL at all
-Rewrote the sound driver to use spu dma
-Sound is much faster ( less sfx are dropped )
-New draw_fix from fox68k (thanks fox!)
-Faster video rendering (aside from the new draw_fix)
-Up-ported to kos 1.3 (svn 165)
-Rearranged sound timer functions for speed
-Prepared the source code to use FAME
-Sped up CD-ROM file loading slightly

*Core Emulation
-Increased accuracy in sound chips (you will notice better PSG sounds)
-Fixed Read Upload which fixes the crash in Breakers (and may fix more)
-Implemented Rudimentary Bios Vector/Game Vector switching
-Partially fixed frame counter speed
-Added timer read and write access by the 68000

*Misc
-Rearranged main functions for expandability
-Undid all the experimental things of v2.2
-'Poked' code everywhere (many small changes)
-A lot of source cleanup