add performance section to readme

.clang-tidy

@@ -1,4 +1,3 @@
-# -*- mode: conf; fill-column: 100; -*-
 # Written for clang-tidy 14.
 
 ---
@@ -46,6 +45,10 @@ CheckOptions:   # ↓ Clashes with static private member prefix. (static int _va
                 - { key: readability-identifier-naming.EnumCase,              value: lower_case }
                 - { key: readability-identifier-naming.FunctionCase,          value: lower_case }
                 - { key: readability-identifier-naming.ParameterCase,         value: lower_case }
+
+                - { key: readability-function-cognitive-complexity.Threshold, value: 30         }
+                - { key: readability-identifier-length.MinimumVariableNameLength, value: 2      }
 ...
 
-# vim: set et tw=100:
+# -*- mode: yaml; fill-column: 100; -*-
+# vim: set fenc=utf-8 tw=100 et ft=yaml:

.cmake-format.json

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+{
+    "format": {
+        "disable": true
+    }
+}

README.adoc

@@ -169,4 +169,25 @@ install ./epubgrep-*.rpm+++` or `+++dnf install ./epubgrep-*.rpm+++`.
 * zipgrep from link:http://infozip.sourceforge.net/[unzip] can search EPUB files
   but does not strip HTML and does not display page numbers or headings.
 
+== Performance
+
+A test with a directory containing 3333 EPUBs and 6269 files in total showed
+this difference between epubgrep-0.6.2 and ripgrep-all-0.9.6:
+
+[source,shellsession]
+--------------------------------------------------------------------------------
+% hyperfine "epubgrep 'floor' ~/Books" "rga 'floor' ~/Books"
+Benchmark #1: epubgrep 'floor' ~/Books
+  Time (mean ± σ):     167.246 s ±  3.848 s    [User: 176.251 s, System: 79.107 s]
+  Range (min … max):   161.533 s … 173.647 s    10 runs
+
+Benchmark #2: rga 'floor' ~/Books
+  Time (mean ± σ):      9.219 s ±  0.506 s    [User: 17.540 s, System: 12.773 s]
+  Range (min … max):    8.571 s …  9.923 s    10 runs
+
+Summary
+  'rga 'floor' ~/Books' ran
+   18.14 ± 1.08 times faster than 'epubgrep 'floor' ~/Books'
+--------------------------------------------------------------------------------
+
 include::{uri-base}/raw/branch/main/CONTRIBUTING.adoc[]