Cisco 1812K9 DHCP server too slow and does not respect MAC-IP binding

Hello, I am fighting with Cisco 1812K9's integrated DHCP server. Until
now dhcpd on Linux was installed in our LAN and it worked like a charm.

This Cisco has an IP 192.168.1.1 and DHCP server is set up using SDM to
assign IPs from pool 192.168.1.2-192.168.1.200. Old Linux dhcpd was
stopped. There is set up special bindings (specific IP, like
192.168.1.180 for specific MAC, like 05-09-04-A5-9C) for several
clients.

I have two problems now:
1. DHCP server is very slow. When launching "ipconfig /renew" on Win XP
clients, I am waiting 5-20 second for an IP address. On old Linux
machine, IP was assigned immediately

2. DHCP server ignores MAC - IP bindings and even clients with
specified MAC are getting IPs from common pool. I am sure I am using
correct MACs, they are the same as in old dhcpd. In SDM I declared this
is Ethernet MAC, but since it didn't worked, I tried the other option
also but with no success.

I was not able to solve this problem by myself. I found the SDM
documentation as very poor and I was not able to find any help there. I
would appreciate any help (link, documentation etc.) which helps me to:
1. Fasten assigning the IP address to the fraction of second
2. Assigning specific IP to specific NIC MAC like it was in dhcpd

Thanks a lot.