Hi Dipak,
Leo has actually answered your question until unless your unerstanding of routing throughput is different.
Routing is nothing but get to know the interface from where next hop of destination can be reachable. Once information is obtained, switching process starts to send the packet to next hop.
Cisco Layer 3 switches use CEF to fasten the process of routing.Taking routing topology & underlying routing/switching mechanism to be same (CEF), bottom line is how fast a hardware can process a frame (i.e. MPPS) and how fast it switches the traffic between port via backplane (gbps switch fabric)
Leo has mentioned the 3750 throughput and depending on SUP engine, 4500 throughput will vary.
3750 datasheet
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps5023/product_data_sheet0900aecd80371991.html
4500 datasheet
http://www.cisco.com/en/US/prod/collateral/modules/ps2797/ps6013/product_data_sheet0900aecd8017a0c5_ps4324_Products_Data_Sheet.html
** In case of 6500, type of line card & DFC add on are the additional factors while computing throughput.
Hope to help
Kind Regards,
