Hi,

There are some things in the config which could be tuned, but not many - I would increase size of lock table to 10Mb and number of page buffers to 512 pages.
But in general it looks like typical problems are not in place here, i.e. your problem is not obvious and it requires professional support, with database statistics investigation, ongoing transaction's markers monitoring, queries audit, locks analysis, etc.

Regards,
Alexey Kovyazin