I was doing some research into VLF and was trying increasing the LOG files with different sizes.
I came across with wired situation where when ever I crease the log size by 4GB, it increases with no time, but I go with less size it takes few or more seconds.
Here is the test.
Simply I created the database with 1 GB log file.
Then I expand the log file with 1-7 GBs and every time I re-create the database.
Here are the results.
It is almost a straight line except for 4 GB.
Let us see the physical log growth at each instances.
So surely there is something wrong when you are incrementing by 4GB. When searching I found the blog post from Paul where he confirms that this is a BUG.
I confirmed that this is resolved in SQL Server 2012.