1/ What version of Resolve are you using?
2/ What are the rest of your computer specs(CPU, RAM, Disk type)?
3/ What OS?
4/ Where are your source video files stored (External drive, internal drive etc.)?
5/ What is the video format of the original files?
6/ Does your timeline include any Fusion comps?
7/ What type of file are you trying to export?
Also, see this troubleshooting FAQ, particularly the part about supplying log files:
viewtopic.php?f=21&t=90190