SuiteCRM performance - record creation time via bean vs raw-sql?

We are experience quite poor performance on one of our SuiteCRM systems which does a file import. I know that the file import script makes heavily usage of beans and I am trying to find ideas why it is so slow.
So each created record is potentially linked to 4-5 existing records in other tables for which the respective load relationship operation is executed.

I would expect that bean creation is in general a bit slower than using raw-sqls but is there a rule of thumb how much slower this should be. It feels very slow.
I read through websites regarding ideas for potential performance bottlenecks but the system seems to be in general really slow, which is why I suspect that the beans could be my bottleneck. Does someone have ideas regarding this kind of problems?

I would start by checking for overgrown tables, run the first query in this post