How much will the cpu load increase when I apply CAR at C7513?

some WAN interfaces R1 R2 some WAN interfaces
             -----------C7513 C7513------------
                    > >
                >fe |fe
            ======switch=======

R2: C7513
  RSP2
  no VIP card
  cpu load: 18%
  FastEthernet:
    outbound: 6Mbps
    inbound: 22Mbps
  Cisco IOS 11.1.18CC
  RED is not available because 11.1.18CC does not provide RED without VIP card.
    
The input queue at the FastEthernet of R2 is insufficent because
there are many inbound packet more than outbound packet into some WAN interfaces at R2.
Therefore, packet drops happens at Fastethernet of R2.

I tried to increase the input queue of the FastEthernet of R2, and
I found that that is useless. So I'll try to apply CAR(committed access rate).

I have two questions.

1. If I apply CAR at FastEthernet of R2 for inbound traffic,
   how much will cpu load of R2 increase?
   I hope that the cpu load does not increase very high.
   The condition for the classification of IP traffic will be very simple.

2. Is it possible that my work applying CAR will fix the packet drops at FastEthernet?
   Will my work make queue available faster than before?

Regards,

/woohyun chang
whchang@bora.net
BORANet Services
DACOM Corporation
Seoul, Korea
TEL+82-2-220-5209