Many complaints about BCM is that it is a performance hog, it's slow, unresponsive, it freezes Outlook... Well here are some tips on how you can improve BCM performance.

First, if you aren't using the email linking feature then shut it off. I believe it's off by default but if you still go into Business Contact Manager -> Manage E-Mail Auto Linking, there are two tabs one for Emails and one for Folders. Click the "Clear All" button on both tabs and click ok.
Second, if you are in a shared database environment, each machine with BCM installed is hitting your SQL server every second. This creates a lot of traffic, and a lot of performance problems. You most likely don't need to get your BCM data updated every second. This update is called a Polling Interval. This Polling Interval was supposedly set higher if you installed the
service pack for BCM, however this probably isn't the case. So you need to manually set it higher. To do this open up Registry Editor on each client machine. The path to the key is HKCU -> Software -> Microsoft -> Business Solutions eCRM. Create a DWORD key in that folder called PollingInterval. Modify it's value and set the Decimal value to 180000 which is 180000ms or 3 minutes. Each minute is 60000ms so the Decimal value for one minute would be 60000. This way the client machine will only hit the SQL server every 3 minutes way down from every second.
Third, set the SQL memory for the client machines. By default each client machine will have SQL Server 2005 Express installed on it, this installs with Outlook BCM. By default the maximum amount of memory that SQL Server 2005 Express can use is 2147483647MB, that's huge and unnecessary for BCM. Download and install the
SQL Management tools on each client machine. Connect to the local SQL Express server and right click on the server within the management studio and choose Properties. Within the pane that comes up, click the Memory link and set the Max Amount of memory to 256MB. That's plenty for BCM. Click OK and it's done.
Fourth, DNS DNS DNS... make sure you are not using your ISPs DNS server. If using a VPN you may need to set static DNS. Network speed to the DNS server is also very important, especially if you are working over a VPN. Check this using nslookup, if the server does not respond in time, then you may need to create a reverse lookup zone for the remote network address.