This could be any of several things, some of which have been identified. Rendering to a WAVE file is done at the speed it can do that, and it would not have the audio glitches that real-time processing has. Some possibilities:

Audio card driver up to date. Windows up to date.
Windows update just reactivated a device you don't want, such as the HD speaker in a monitor screen. Yes, Windows updates do that.
Try the WAS driver in Preferences, Audio. If you are using the WAS driver, try the ASIO driver.
In ASIO, get into the ASIO control panel and experiment with the buffer settings. Raise them to start.
The setting AudioTrack showed above: this song has playback problems.
Something running in the background; try rebooting and running only BIAB
Reduce programs that start automatically on bootup. If you need help how to fix that, let us know.
Is it one RealTrack only? Does it happen if you run many RealTracks in the same song?
I could go on ...

As Herb said, tell us about your soundcard. Also about your processor type and speed and cores.

Are you anywhere near Rocky River?

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.