Importing requirements from Excel to DNG is very slow

Hello Team,
We are trying to import requirements from our inhouse legacy system to DNG. We had already exported the requirements in excel and we are using a script to import the requirements into DNG project areas using OSLC. The incoming projects areas are GC enabled. Total number of artifacts are 45000.

As for our infrastructure, we are currently at Rational CLM 6.0.5 ifix 002 and having following server configuration (VM) Application OS CPU RAM Disk
1 IHS (Reverse Proxy) Windows 2012 8 16 50 IBM HTTP
2 JTS/CCM/GC/LDX/RB Windows 2012 8 16 100 IBM CLM
3 DNG Windows 2012 8 32 200 IBM CLM
4 DM Windows 2012 8 16 200 IBM CLM
5 DB Server Windows 2012 8 16 150 Extendable for DNG SQL Server 2014 (Single Node)
6 DCC/LQE Windows 2012 16 32 100 IBM CLM
7 RELM Windows 2012 8 24 100 IBM CLM

When the script is running, we do not see any load (cpu, memory, disk) on the server however the script is very slow and importing 7-8 artifacts in a minute. Has anyone else encountered the same issue while importing requirements into GC enabled project areas in DNG ?

Regards
Vishnu Kumar