I'm loading an empty page with
Loading Time: Base Classes 0.0014
Controller Execution Time ( Test / Phpinfo ) 0.0880
Total Execution Time 0.0897
Loading Time: Base Classes 0.0013
Controller Execution Time ( Test / Phpinfo ) 0.0160
Total Execution Time 0.0175
The server environment, and how busy it is (how many processes are going on at any given millisecond) could affect how fast your page is generated. That said, it does seem like your server is especially slow, which could explain why you see a greater variance. I consider my dev server to be slow, and I get these kind of benchmarks:
Loading Time: Base Classes 0.0008 Controller Execution Time ( Test / Index ) 0.0002 Total Execution Time 0.0010
For me, total execution time varies between 0.0008 and 0.0016. This kind of variance could be the result of system antivirus, or basically any other program or process doing something. Because PHP and your HTTP server are sharing system resources with everything else on the computer/server, you will see a variance, and that's normal.
If you're curious, you should look into the CPU and memory usage of your computer, and see how it varies, even when you think it is idle.