[otrs] delete tickets

Hi, i'm using old otrs 3.1.7 and there is around 170k tickets, that I need to delete. I'm using generic agent, but the process is VERY slow. It takes around 5-10 second to delete one ticket and there is actually no load on hardware (load average: 0.25, 0.20, 0.12), everything is idle. Are there any ways to make this process faster?