If dial-up modem or other exterior serial device looks to be doing badly, it unable to conversing with PC as rapidly as it can. Windows provides users ability to change speed at which devices converse with PC over serial port. Modify this speed to maximize performance of device.

Instructions
1. Click "Start," then click "Control Panel." Double-click "Device Manager."
2. Click plus sign beside "Ports" in Device Manager, and find port number you want to adjust.
3. Right click on entry for port, and click "Properties."
4. Click on "Port Settings" tab.
5. Tick drop-down menu beside "Bits per second," and choose preferred value. The suggested setting for 56k dial-up modems is "115200" or higher. Tick "OK" and reboot PC. New port speed will take result after PC reboots.