At the moment, the latest version of Battlefield Vietnam is version 1.21, and this patch can be downloaded from here: EA Games or FilePlanet among other places. Despite this, it is still vital to make sure that you are running the latest version of the game.
Unfortunately the patches have not completely fixed the major source of complaint: BF:V's performance. Since Battlefield Vietnam was released early in 2004, it has received several patches which have resolved some of the game issues many players have complained about.
Battlefield Vietnam Tweak Guide Patches, Maps & Mods