Hi Raj,
Can you please provide more information like what type of query are you running, what is the exact error message etc.
A table with 90 m records and of size 4 GB is not at all big. How did you check the memory size. Can you please run the standard checks like all the data is merged to main memory for your specific test, the partitions are loaded to the memory.
It will help if you provide the details on table memory utilization (with some info on partitions) and the query information.
Can you also try to reduce the data selected using some filters and check the visual plan. It will give you some indication on where the time is spent and how much data volume is exchanged between the engines.
Regards,
Ravi