Regarding data fetching from BKPF table

For fetching G/L Account for the corresponding document number which has BUZID value 'W' in BSIS table I am going to BKPF table and splitting AWKEY into document number and fiscal year for inputting that into RSEG table and there getting LFBNR and LFGJA and combining it as AWKEY for inputting it into BKPF table for getting corresponding document number and inputting it into BSIS table for getting corresponding G/L account which has BUZID 'M' for GR/IR account.

While going to BKPF table with AWKEY as input it is giving performance issue, Can any one reply me with the solution that is there any way to solve the performance issue and any other way for fetching G/L account for that corresponding GR/IR account.