Avg. Response Time of the SYSTEM is increasing

Hi Experts ,

Need help to deal with the increasing Avg. Response Time of the systems.

Avg. Response Time of the SYSTEM is increasing gradually  specially for the following :

Following BRFPLus Decision tables and corresponding indexes are growing very fast about 15 GB per month as a result Avg. Response Time in Dialog Task is gradually  increasing ,  re indexing  improved some performance, but  just wondering if is any other way known way  to  improve the performance  of these tables

FDT_EXPR_0248A – 15 GB

FDT_EXPR_0248A~0 – 17 GB

FDT_EXPR_0247A – 14 GB

FDT_EXPR_0247A~0 – 16 GB

FDT_EXPR_0244A – 8 GB

Also BALDT is growing very fast , 2GB each month  , is there any known recommendation ?

BALDAT  - 8GB

Thanks

Al Mamun