A 3 GB logfile would fit nicely into 3 GB of RAM. What application is bloating that up to 16 GB? Maybe try out someting different. My prefered tools are grep and less. They can handle even big files with low resource costs.
Time for you to setup logroate. There are a few topics in the forum that will give you some configuration examples.
The trick with opening large text files is not loading them all into RAM. IIRC on Windows PilotEdit can do that.
BTW, I scripted node restarts so that after each restart logging goes to a different file. I recommend this approach in case you can’t properly do log rotating.