A very long thread in the Gearbox forums has some of the usual complaints about Halo CE in it, mostly about lag and "warping", and a response from Randy "DuvalMagic" Pitchford, CEO of Gearbox, providing some of the background on the project to port Halo to the PC and how it affected the game's eventual network performance:

Halo's networking system was from scratch, first generation, developed in six months by three engineers and launched into a very competitive world of PC on-line gaming with a game design that is not condusive to the inherent problems of the internet. This networking system had to be meshed into an existing C code-base that had been evolved over 10 years of Bungie games until, in it's last usage, was completely overhauled, retuned and refitted with bubblegum, duct-tape and infinite sleepless work nights specifically for the Xbox platform (which was being invented while all of this refitting was going on).

This does confirm some suspicions held by longtime Bungiefen that Xbox Halo's netcode owed quite a bit to Marathon's deterministic, synchronous netplay, that also worked well only on LANs prior to the addition of native TCP/IP play in Aleph One. Pitchford also cites several requirements, including support for 56k players and fitting the game on a single CD, that he says Bungie and Microsoft slipped into the requirements after the deal was signed. All in all, however, Pitchford says that Gearbox and Bungie both worked hard to make Halo PC and Halo CE the best they could possibly be, but that practicalities and system requirements meant that less was delivered than expected, and there was little or nothing that could be done about it, given the game's design specifications.