Speed up debugging in IntelliJ

Yesterday, I observed painfully slow debugging in IntelliJ. Every step over or step in took almost 10 seconds to perform.

It was a simple Java console application having about some 88k entries in few arrays. I had successfully debugged applications having millions of entries in arrays, lists and maps before without any performance issues.

Then I looked at the toString() implementation of the custom object which I was holding in the array

 public String toString() {
        StringBuilder s = new StringBuilder();
        s.append(V + " vertices, " + E + " edges " + NEWLINE);
        for (int v = 0; v < V; v++) {
            s.append(String.format("%d: ", v));
            for (int w : adj[v]) {
                s.append(String.format("%d ", w));
        return s.toString();

This toString() implementation was looping over all the 88k items and IntelliJ is configured to evaluate toString() after every step.

Turning off the setting Enable toString() data views solved this problem of slow debugging.

Incase you are experiencing slow debugging issues on IntelliJ, do make sure that this setting is turned off.