If network resources are operating at or are near maximum capacity, this can
be the cause of physical layer problems. In some instances of sub-optimal
network performance, data may flow at expected rates, but it will start and
stop unexpectedly. In other instances the data will flow continuously, but not
at a desirable rate.
Poor performance may be caused by the same
conditions that prevent a connection from being established in the first place,
or from the same conditions that cause connections to drop.

The
following procedures assume that this connection has been operating properly
prior to this problem, and the following have already been checked:
- Verified that nothing has been recently changed on the problem station, or
on the server or service that may have caused this problem, such as
reconfiguring or adding new software or hardware.
- Eliminated potential station memory allocation problems and software
conflicts on the station by unloading all but the minimum software required to
operate a test application across the network. For this test disable any virus
checking or security software, but re-enable it immediately after the test.
- Tested the user’s station for viruses and look for applications that are
consuming disproportionate amounts of the microprocessor resources or hanging
the system long enough to exceed connection timers.
The most common reasons for slow or poor performance include overloaded
or underpowered servers, unsuitable switch or router configurations, traffic
congestion on a low capacity link, and chronic frame loss.