I am running multiple Tomcat instances for confluence, and sometimes face that confluence page loading takes too long - I can't have any chance to edit a page.
If it is, you should take a look following two items
<confluence home>/conf/server.xml
<confluence home>/bin/setenv.sh
You should check if your collaborative editor port does not make any conflict with other application including confluence instances. If you run more than one confluence on your server, you should change the port number.
The action you should do is simple - just adding one more a line below Dsynchrony.enable.xhr.fallback
CATALINA_OPTS="-Dsynchrony.port=28191 ${CATALINA_OPTS}"
Below is the actual example I made
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# Set the JVM arguments used to start Confluence. For a description of the options, see
# http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html
CATALINA_OPTS="-XX:-PrintGCDetails -XX:+PrintGCDateStamps -XX:-PrintTenuringDistribution ${CATALINA_OPTS}"
CATALINA_OPTS="-Xloggc:$LOGBASEABS/logs/gc-`date +%F_%H-%M-%S`.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=2M ${CATALINA_OPTS}"
CATALINA_OPTS="-XX:G1ReservePercent=20 ${CATALINA_OPTS}"
CATALINA_OPTS="-Djava.awt.headless=true ${CATALINA_OPTS}"
CATALINA_OPTS="-Datlassian.plugins.enable.wait=300 ${CATALINA_OPTS}"
CATALINA_OPTS="-Xms1024m -Xmx1024m -XX:+UseG1GC ${CATALINA_OPTS}"
CATALINA_OPTS="-Dsynchrony.enable.xhr.fallback=true ${CATALINA_OPTS}"
CATALINA_OPTS="-Dsynchrony.port=28191 ${CATALINA_OPTS}"
CATALINA_OPTS="-Dorg.apache.tomcat.websocket.DEFAULT_BUFFER_SIZE=32768 ${CATALINA_OPTS}"
CATALINA_OPTS="-Djava.locale.providers=COMPAT,SPI ${CATALINA_OPTS}"
CATALINA_OPTS="${START_CONFLUENCE_JAVA_OPTS} ${CATALINA_OPTS}"
CATALINA_OPTS="-Dconfluence.context.path=${CONFLUENCE_CONTEXT_PATH} ${CATALINA_OPTS}"
CATALINA_OPTS="-XX:ReservedCodeCacheSize=256m -XX:+UseCodeCacheFlushing ${CATALINA_OPTS}"
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