We had memory leaks, application performance, multiple connections that were done serialized instead of taking advantage of concurrency, low performance SQL and MongoDB. Instana allow us to spot the issues, confirm that changes address them and measure the improvements.
Memory leaks are hard to track and having a tool that help to find out this one is causing it makes a huge different - by spending less time and confirming that the changes where effective.
Application performance are complex to nail down the culprit and having a way to quickly weed out the modules that are working makes it easier. Tracing down the calls from one API to another is huge. It was very interesting to note patterns of the connection.
Some applications were not optimized when calling other services - doing one at the time. Using Instana presented it visually and it was an super easy performance improvement to be implemented and having the same functionality using much less time was great.
We had SQL queries that were causing APIs to have low performance. This was pretty fast to identify the issue, add indexes to the database and seeing the improvement is great.
MongoDB also had issues that were quickly addressed and fixed timely.
I personally really enjoy how fast is to troubleshoot, identify points of failures and after applying the fix, find that it worked without guessing. Review collected by and hosted on G2.com.