; Optimize 'completion-preview--try-table'

; Optimize 'completion-preview--try-table'

* lisp/completion-preview.el (completion-preview-completion-styles):
New variable.  Default to only include the 'basic' completion style.
(completion-preview--try-table): Let-bind 'completion-styles' when
calling 'completion-all-completions'.  With the default value of
'completion-preview-completion-styles', this yields a significant
performance improvement (up to 4 times faster compared to the
'substring' style when tested with 'elisp-completion-at-point').

Suggested by Ergus <spacibba@aol.com>