Hi Ergus,

On 17.08.2021 03:45, Ergus wrote:

> I made a manual fast profiling and I see that most of the time in
> project-buffers actually goes to tramp-sh-file-name-handler.
> 
>           207  42%         - project-buffers
>           207  42%          - apply
>           207  42%           - #<compiled -0x1f5d919efefc0a09>
>           200  40%            - file-in-directory-p
>           200  40%             - tramp-file-name-handler
>           197  40%              - apply
>           197  40%               - tramp-sh-file-name-handler
>           197  40%                - tramp-handle-file-in-directory-p
>           183  37%                 - tramp-run-real-handler
>           183  37%                  - file-in-directory-p
>           124  25%                   - file-equal-p
>           124  25%                    - tramp-file-name-handler
>           121  24%                     - apply
>           121  24%                      - tramp-sh-file-name-handler
>           121  24%                       - tramp-handle-file-equal-p
>            85  17%                        - tramp-run-real-handler
>            85  17%                         - file-equal-p
>            52  10%                          - file-truename
>            52  10%                           - tramp-file-name-handler
>            41   8%                            - apply
>            41   8%                             - tramp-sh-file-name-handler
>            41   8%                              - 
> tramp-sh-handle-file-truename
>            28   5%                               + file-remote-p
>            10   2%                               + file-local-name
>             3   0%                               + file-name-as-directory
> 
> It goes specifically to file-in-directory-p as you said. So maybe the
> improvement there may be also desirable if the difference after the
> optimization can reduce the time for file-in-directory-p (or the caller)
> at least to the half.

Thanks for testing.

Try the attached new version please. It should eliminate that particular 
bottleneck.