diff --git a/ccp4/README.md b/ccp4/README.md
index 9020c85..d97a2cd 100644
--- a/ccp4/README.md
+++ b/ccp4/README.md
@@ -48,8 +48,11 @@ hand-downloaded tarball into the distfiles dir under the `name:` given in
 The `install` step untars 3.7 GB into ~15-20 GB of small files on shared
 /opt/psi storage: the tar alone runs 10-30 min with no output (gzip is
 single-threaded, small-file creation on network storage is the
-bottleneck), and `BINARY.setup` afterwards walks the whole installation
-for several more minutes. Watch progress from a second shell:
+bottleneck). `BINARY.setup` afterwards is just as bad — it walks the
+whole installation patching paths and then **byte-compiles the bundled
+Python environment** ("compiling py-files"), thousands of tiny .pyc
+writes on network storage; expect another 15-30+ min. Budget roughly an
+hour for the whole install on Ra. Watch progress from a second shell:
 
 ```bash
 watch -n 30 'du -sh /opt/psi/MX/ccp4/9.0/'