diff --git a/doc.md b/doc.md
index edbb95c..8c492c9 100644
--- a/doc.md
+++ b/doc.md
@@ -404,7 +404,7 @@ Make sure your server is sending the ```Connection:keep-alive``` header
 * On IE11, a same origin policy error is erroneously triggered under unknown conditions. Seems to be related to running the test from unusual URLs like a top level domain (for instance http://abc/speedtest). These are bugs in IE11's implementation of the same origin policy, not in the speedtest itself.
 * On IE11, under unknown circumstances, on some systems the test can only be run once, after which speedtest_worker.js will not be loaded by IE until the browser is restarted. This is a rare bug in IE11.
 ### Firefox-Specific
-* On some Linux systems with hardware acceleration turned off, the page rendering makes the browser lag, reducing the accuracy of the ping/jitter test
+* On some Linux systems with hardware acceleration turned off, the page rendering makes the browser lag, reducing the accuracy of the ping/jitter test, and potentially even the download and upload tests on very fast connections.
 
 ## Making changes
 Since this is an open source project, you can modify it.