Moving or lengthening the spline in UE5.1 slows it down excessively. UE5.1 Spline Bug

I would really appreciate if an Unreal Engine Developer could answer on this.
Because my customers using the product with UE 5.1 have complaints and I haven’t been able to find a solution yet.

At least if this is a BUG that needs to be fixed I can report it to customers

Thank you!