Deletion of Standard tables

Dear Experts,

We are planing to delete data in standard tables to improve the system performance.

Standard tables are :

RSREQDONE - Monitor: Saving of the QM entries

RSPCLOGCHAIN - Cross-Table Log ID / Chain ID

TBTCO - Job Status Overview Table

RSPCCHAIN - Process chain

RSDIOBJT - InfoObject texts

RSDIOBJ - Directory of all InfoObjects

I need some information like

1. Is there any impact by deleting above tables?

2. If we can delete how much data we can delete?

3. And the frequency of deletion.

If already threads are available please share it.

Thank You in advance!

Hari