should improve gitsynch performance

[hoatle]

The current performance is not good enough, it takes time to check and sync.

I guess we can improve its performance by:

git checkout #{branch} -b #{branch}

And use current branch with desired branch to compare if we need to update when they're different.

Currently, we use ref to check, I guess it's the cause of slowness.

[hoatle]

make sure go add measurement to see how much performance is gained with the changes.

[datphan]

This process takes time because of the git fetch origin command, the other commands do not take any visible time, and I couldn't found any way to improve it except make the git fetch origin only run after some time pass, like 2 days, 1 weeks, ...

git checkout #{branch} -b #{branch} I'd run it without any differences