Hi Vinita,
I don't know any place in SRM where the INFO Vendor <-> CoCode is stored.
So You may need to make an RFC or place this data into Z-Table on SRM side.
If you have the fast backend RFC connection, I would say < 100 ms to retrieve the data.
I would suggest to use BAPI_VENDOR_GET_DETAIL via RFC with the smart buffering in check BADI.
With the smart buffering I mean read once for the first item and save the result in the internal table, so the other items with the same vendor not to be checked.
So your check will be performed ideally only once per check badi call. As for me, that's would be not a big impact on Performance. RFC Should be already opened (due to accounting checks).
To make the performance even more better, you can save the check results as a static attribute of the CHECK-BADI class or your own class. So the RFC check per vendor/cocode will be performed only once per apprication. But in that case you loose you memory (not much, but...).
As always fast or tiny 
Regards
Konstantin