add performance section to readme

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[]