As the Mannlicher and Mannlicher-Schoenauer bolts are essentially the same as the M88 one, they all share a slightly slower lock time, compared to a M98 Mauser. This is because a heavy cocking piece and the safety are hung on the firing pin. This markedly increases the mass that has to be accelerated by the mainspring. A double set Trigger always increases locktime too. This locktime increase is usually hardly noticable, so I suspect a weakened mainspring. Locktime may also be slowed down by old, hardened grease/oil inside the bolt or the trigger assembly. So first you should disassemble your rifle to clean and reoil all action parts.