Print time software conflict

[Robgibbo]

Hi All
Brand new to 3d printing, got myself a Ender 3 V2 Neo all standard, and have to say I’m bitten by the bug.
I’m using Cura software, the problem I’m having is……
When I splice certain things, the software time is say 5 hrs 30 mins, but when I transfer it to the printer and start printing, this time can double, even triple.
Anyone had this before? And if so did you find a solution, to print the item in the time the software is saying?
Thanks in advance