diff --git a/php/php71-debug/Dockerfile b/php/php71-debug/Dockerfile
index 0bb8492..d61b31a 100644
--- a/php/php71-debug/Dockerfile
+++ b/php/php71-debug/Dockerfile
@@ -9,5 +9,7 @@ RUN echo "xdebug.remote_enable=1" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php72-debug/Dockerfile b/php/php72-debug/Dockerfile
index 300f70d..4a7e3aa 100644
--- a/php/php72-debug/Dockerfile
+++ b/php/php72-debug/Dockerfile
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php73-debug/Dockerfile b/php/php73-debug/Dockerfile
index e6a17e0..92ceaf6 100644
--- a/php/php73-debug/Dockerfile
+++ b/php/php73-debug/Dockerfile
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php74-debug/Dockerfile b/php/php74-debug/Dockerfile
index 99bbaee..d5c899d 100644
--- a/php/php74-debug/Dockerfile
+++ b/php/php74-debug/Dockerfile
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php80-debug/Dockerfile b/php/php80-debug/Dockerfile
index 7d12ae5..47a89e3 100644
--- a/php/php80-debug/Dockerfile
+++ b/php/php80-debug/Dockerfile
@@ -1,6 +1,6 @@
 FROM totara/docker-dev-php80:latest
 
-RUN pecl install -f xdebug-3.3.2 && docker-php-ext-enable xdebug.so
+RUN pecl install -f xdebug-3.4.0beta1 && docker-php-ext-enable xdebug.so
 RUN pecl install -f pcov && docker-php-ext-enable pcov.so
 
 RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php81-debug/Dockerfile b/php/php81-debug/Dockerfile
index 96e0fec..92d6a67 100644
--- a/php/php81-debug/Dockerfile
+++ b/php/php81-debug/Dockerfile
@@ -1,6 +1,6 @@
 FROM totara/docker-dev-php81:latest
 
-RUN pecl install -f xdebug-3.3.2 && docker-php-ext-enable xdebug.so
+RUN pecl install -f xdebug-3.4.0beta1 && docker-php-ext-enable xdebug.so
 RUN pecl install -f pcov && docker-php-ext-enable pcov.so
 
 RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php82-debug/Dockerfile b/php/php82-debug/Dockerfile
index 36896e2..83582f7 100644
--- a/php/php82-debug/Dockerfile
+++ b/php/php82-debug/Dockerfile
@@ -1,6 +1,6 @@
 FROM totara/docker-dev-php82:latest
 
-RUN pecl install -f xdebug-3.3.2 && docker-php-ext-enable xdebug.so
+RUN pecl install -f xdebug-3.4.0beta1 && docker-php-ext-enable xdebug.so
 RUN pecl install -f pcov && docker-php-ext-enable pcov.so
 
 RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file
diff --git a/php/php83-debug/Dockerfile b/php/php83-debug/Dockerfile
index 8600ee4..1d91537 100644
--- a/php/php83-debug/Dockerfile
+++ b/php/php83-debug/Dockerfile
@@ -1,6 +1,6 @@
 FROM totara/docker-dev-php83:latest
 
-RUN pecl install -f xdebug-3.3.2 && docker-php-ext-enable xdebug.so
+RUN pecl install -f xdebug-3.4.0beta1 && docker-php-ext-enable xdebug.so
 RUN pecl install -f pcov && docker-php-ext-enable pcov.so
 
 RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
@@ -9,5 +9,7 @@ RUN echo "xdebug.mode=debug" >> /usr/local/etc/php/conf.d/xdebug.ini \
 # Set some sensible defaults
 RUN echo "pcov.enabled=1" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.exclude='~(vendor|tests|node_modules|.git|client|.scannerwork)~'" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
-    && echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
+    # The next line can be enabled (and applied with tbuild and tup of this container) to optimise memory usage \
+    # Note that PHP's memory limit needs to be high enough.
+    #&& echo "pcov.initial.memory=1073741824" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini \
     && echo "pcov.initial.files=30000" >> /usr/local/etc/php/conf.d/docker-php-ext-pcov.ini
\ No newline at end of file