diff --git a/build.xml b/build.xml
index f0eeb3336f10bb0bfd8403359fb075c017d599a8..db8bf0c420c8754d0f155b2a9d43e6db7046ed23 100644
--- a/build.xml
+++ b/build.xml
@@ -22,6 +22,7 @@
   <property name="pgsqlrootuser" value="postgres" />
   <property name="phpunit_extra_params" value="" />
   <property name="mink_driver" value="zombiejs" /><!-- may also be set to selenium -->
+  <property name="snooze_multiplier" value="1" /><!-- can be used to slow down tests (selenium only) -->
   <property name="php-cs-fixers" value="no_blank_lines_before_namespaces,function_call_space,trailing_spaces,unused_use,lowercase_keywords,encoding,parenthesis,php_closing_tag,visibility,duplicate_semicolon,extra_empty_lines,no_blank_lines_after_class_opening,no_empty_lines_after_phpdocs,operators_spaces,spaces_before_semicolon,ternary_spaces,concat_with_spaces,short_array_syntax,phpdoc_no_access,remove_leading_slash_use" />
 
 
@@ -111,12 +112,12 @@
 
   <!-- PHPUnit -->
   <target name="phpunit" description="Run tests">
-    <exec dir="${srcdir}/module/VuFind/tests" command="NODE_PATH=${nodepath} VUFIND_MINK_DRIVER=${mink_driver} VUFIND_LOCAL_DIR=${srcdir}/local VUFIND_URL=${vufindurl} phpunit -dzend.enable_gc=0 --log-junit ${builddir}/reports/phpunit.xml --coverage-clover ${builddir}/reports/coverage/clover.xml --coverage-html ${builddir}/reports/coverage/ ${phpunit_extra_params}" passthru="true" checkreturn="true" />
+    <exec dir="${srcdir}/module/VuFind/tests" command="NODE_PATH=${nodepath} VUFIND_MINK_DRIVER=${mink_driver} VUFIND_SNOOZE_MULTIPLIER=${snooze_multiplier} VUFIND_LOCAL_DIR=${srcdir}/local VUFIND_URL=${vufindurl} phpunit -dzend.enable_gc=0 --log-junit ${builddir}/reports/phpunit.xml --coverage-clover ${builddir}/reports/coverage/clover.xml --coverage-html ${builddir}/reports/coverage/ ${phpunit_extra_params}" passthru="true" checkreturn="true" />
   </target>
 
   <!-- PHPUnit without logging output -->
   <target name="phpunitfast" description="Run tests">
-    <exec dir="${srcdir}/module/VuFind/tests" command="NODE_PATH=${nodepath} VUFIND_MINK_DRIVER=${mink_driver} VUFIND_LOCAL_DIR=${srcdir}/local VUFIND_URL=${vufindurl} phpunit -dzend.enable_gc=0 ${phpunit_extra_params}" passthru="true" checkreturn="true" />
+    <exec dir="${srcdir}/module/VuFind/tests" command="NODE_PATH=${nodepath} VUFIND_MINK_DRIVER=${mink_driver} VUFIND_SNOOZE_MULTIPLIER=${snooze_multiplier} VUFIND_LOCAL_DIR=${srcdir}/local VUFIND_URL=${vufindurl} phpunit -dzend.enable_gc=0 ${phpunit_extra_params}" passthru="true" checkreturn="true" />
   </target>
 
   <!-- Install and Activate VuFind -->
diff --git a/module/VuFind/src/VuFindTest/Unit/MinkTestCase.php b/module/VuFind/src/VuFindTest/Unit/MinkTestCase.php
index 455e1af1842381f759b779e433788696d3ec8b87..c740ec51f5e7028ae03c4cf51f5e80c3b4a363d2 100644
--- a/module/VuFind/src/VuFindTest/Unit/MinkTestCase.php
+++ b/module/VuFind/src/VuFindTest/Unit/MinkTestCase.php
@@ -140,7 +140,11 @@ abstract class MinkTestCase extends DbTestCase
     {
         // Sleep is not necessary for Zombie.js.
         if (!$this->isZombieDriver()) {
-            sleep($secs);
+            $snoozeMultiplier = intval(getenv('VUFIND_SNOOZE_MULTIPLIER'));
+            if ($snoozeMultiplier < 1) {
+                $snoozeMultiplier = 1;
+            }
+            sleep($secs * $snoozeMultiplier);
         }
     }