Tonight, I was finally fed up with my Terminal window taking nearly 10 seconds to show the initial prompt. I regularly use Terminal to SSH into other computers and to commit and pull code changes in git repositories. The delay was annoying so I looked for help.
Luckily, other people on the Internet have noticed the same issue so it wasn’t hard to find a solution. The first one I came across was on this blog post on OSXDaily. Initially, I was a little skeptical of log files having anything to do with the Terminal startup time, but other Google results also came up with the same solution.
The solution is to remove the *.asl (Apple System Log) files from the /private/var/log/asl/ folder. The Terminal command to remove those log files is:
sudo rm -rf /private/var/log/asl/*.asl
This is obviously a short term solution, as new log files will presumably accumulate over time again. I found additional information on SuperUser and ProposedSolution that you can check out, if you are looking for a deeper explanation and/or a long-term solution.