Checking setup of your audio device is a good place to start for any troubleshooting activity. Slow recording may result from changes to software or hardware configurations. Audacity installs default settings on a "best guess" basis which may or may not work with your system. Select "Edit" from the menu bar and "Preferences" from the drop-down menu. Under "Devices," ensure the proper sound interface is selected for both playback and recording. These settings are also available on the Audacity desktop under the transport controls.
Latency is the time delay that occurs with processing of audio signals. It is affected by factors like computer speed, free memory, and the design and performance of audio interfaces used to record. In Audacity, the effect is most often heard when an overdub comes behind other tracks in timing. The wave of the overdubbed track can be dragged to match other tracks. For a more permanent solution, look at the latency settings under the "Recording" tab in the Preferences window. Adjust the value beside "Latency Correction" to fine-tune how Audacity places your overdubs.
When importing audio from another source into Audacity, it is crucial that sample rates match. When rates are off, the effect is analogous to playing a vinyl record at the wrong speed. Audio sampled at a higher rate will sound slowed down. Ensure that the original sample matches the current sample rate in Audacity, or change the rate in Audacity to match the sample. The project rate can be selected in the bottom left corner of the Audacity desktop.
Optimizing your computer for working with audio is an important consideration. Any draw on system resources can potentially slow down recording performance. If your system has two physical hard drives, one of the best tweaks you can make is changing your temporary files directory to the second hard drive. This allows Audacity to use the first drive to run itself while data is stored on the second drive. In the Preferences window, select "Directories" and change the destination of the temporary files directory.