SAP PI/PO provide us two working tools very useful, if you are developer or integration consultant you have to use it everyday. One day, when you open many mapping or configuration objects. These tools a bit slow. Tools designed buy Java Network Lunch Protocol (jnlp) meaning libraries of application will be downloaded from server into your local machine and run by JRE (Java Run-time Environment)
https://docs.oracle.com/javase/tutorial/deployment/deploymentInDepth/jnlp.html
The problem here is initiation heap size (Min and Max) not big enough for you when open many design objects at the same time.
Instead of using default initiation setting of ESR and IB, before open these tools we can manual adjust those values to increase heap memory and performance.
STEP 01: Download ESR from SAP PO main page
STEP 02: Save file to local computer and edit with text editor
STEP 03: Increase initial and max heap size of memory
STEP 04: Save changed and open ESR | IB then enjoy
Normally, we can keep it as default from SAP PO. It will be nice to you when do with very large or complicate mapping.
A bit inconvenience because you need to change those parameters every time download JNLP.
Thanks,
Cuong Dang
SAP Zero to Hero 