performance improvements for FilterLocList()
performance improvements for FilterLocList()

Remove the call to deepcopy() and use some alternative logic instead.

This improves performance massively for large location lists. More
aggressive caching is needed really though since this function is called
multiple times to return the same data.

wezhang/vim-setup,wezhang/vim-setup,nikmartin/dotfiles,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup