diff --git a/Changelog.md b/Changelog.md
index eb40d952..515ae70d 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -105,6 +105,8 @@
 - Joex:
   - adds `clear-stanford-nlp-interval = "15 minutes"` which is the
     joex idle time to clear the nlp cache
+  - The default `pool-size` is set to 1. You can increase it on
+    stronger machines.
 
 
 ## v0.17.1
diff --git a/modules/joex/src/main/resources/reference.conf b/modules/joex/src/main/resources/reference.conf
index 9561be58..4aeb5a1b 100644
--- a/modules/joex/src/main/resources/reference.conf
+++ b/modules/joex/src/main/resources/reference.conf
@@ -58,7 +58,7 @@ docspell.joex {
     name = ${docspell.joex.app-id}
 
     # Number of processing allowed in parallel.
-    pool-size = 2
+    pool-size = 1
 
     # A counting scheme determines the ratio of how high- and low-prio
     # jobs are run. For example: 4,1 means run 4 high prio jobs, then
@@ -203,7 +203,8 @@ docspell.joex {
     ocr {
 
       # Images greater than this size are skipped. Note that every
-      # image is loaded completely into memory for doing OCR.
+      # image is loaded completely into memory for doing OCR. This is
+      # the pixel count, `height * width` of the image.
       max-image-size = 14000000
 
       # Defines what pages to process. If a PDF with 600 pages is