Dungeon Fantasy Roleplaying Game
Depends on what one means by "longer"...
Longer than say a sit-down game? Mos def.
Longer than any other Play-by-Post? Like say a D&D PbP? No.
D&D combat take time because they are a war of attrition - Whittle that enemies HP down! And D&D (N)PCs have a lot of HP...
GURPS combats can be brutally fast or slogs (just like D&D), it depends on luck and tactics. Combat can literally end in 1 hit, say a Scout putting two arrows into the eyes of the BBEG in turn 1, killing him. Or, with some bad rolls, or just facing enemies you can't one-shot, it can drag on a bit. Usually it doesn't, it takes a really hard foe and really unoptimized PCs using bad tactics (or just being stubbornly stuck in) to make a fight slog.