Why is it so slow to open the graph in browser?

For the same graph, it's very quick to open the graph database in my local machine:
http://xx.xx.xx.xx:7474/browser/

However, in another machine which is in close network, it sometimes takes a long time to display the graph in the browser. In a few times it immediately displays the graph and runs very quick.

While it might be due to network traffic, are there any other possible reasons to cause this? For example, some database configurations may affect this or can improve this?

Make sure you compare the same query in both cases to make sure the reason isn't simply the size of the results return. I assume you did that.

If not due to network bandwidth or latency, most likely it is something specific to that client. Did you compare the browser version, and check for anything else that is different? (e.g. what else is running on the client, any proxy settings, firewall or other software that is different?)

Query times are normal, compared to local machines. The problem is the initial loading time, namely, from opening the database url to fully displaying the Neo4j browser interface with the graph nodes.

It seems it is taking time to load the whole data into memory? but that shouldn't be the case. Without issuing a query, this shouldn't happen. We tried from different machines and it's the same. A few times it's quick though. Most of the time it's slow.

What do you mean when you say "with the graph nodes", are you setup to automatically run a query?
normally nodes are not loaded or displayed when you go to a neo4j server with a Browser (e.g. Chrome)

The same is generally true of the neo4j desktop client as well, no nodes are loaded or displayed until you run a query.

Do you have a query setup to run when the browser loads? (I've not done this, I think it is uncommon, and someone has to do the work to set it up)