Drop table vs Delete record

My application has two threads, one inserts thousands of records per second into a table (t1) and the other thread periodically deletes expired records (also in thousands) from the same table (expired ones). So, we have one thread adding a row while the other thread is trying to delete a row. In a short time the overall performance of any sql statements on that instance degrades. (ex. Select count(*) from t1 takes more then few seconds with less than 10K rows).

My question is: Would any sql statement perform better if I would rename the table to t1_%indx periodically, create a new table t1 (for new inserts) and just drop the tables with expired records rather then doing a delete record? (t1 is a simple table with many rows and no constraints).

(I know I could run vacuum analyze)

Thanks,

Orhan A.