Rails 4资产编译在开发模式下非常慢（> 1分钟）。如何排除故障？

I am using a Rails 4 app with bootstrap. At some point, the assets compilation got borked and now it it takes over a minute to reload a page if i make any changes to the SCSS files. Changing the JS files do not cause this delay. I have no idea what is causing this, but when i tried to just precompile the assets myself, the process takes about 2 seconds to complete. not sure why when it happens on the fly it takes over a minute, sometimes more than 2. I am using a Rails 4 app with bootstrap. At som