Boost IntelliJ: Fix Randomness Plugin Slow UI & Freezes

Hey guys, ever felt that frustrating lag when you're trying to quickly navigate or use an action in IntelliJ IDEA, only for the UI to momentarily freeze on you? It's super annoying, right? Especially when you're in the zone, coding away, and suddenly your IDE decides to take a coffee break. Well, you're not alone! Many users, particularly those leveraging powerful plugins, sometimes hit these snags. Today, we're diving deep into a specific issue that can cause these very problems: a slow UI performance in IntelliJ's Randomness plugin due to TemplateInsertAction operating on the Event Dispatch Thread (EDT). This isn't just about a minor delay; it can lead to a completely unresponsive UI, making your development flow feel like wading through treacle. We're going to explore what causes this, what the technical report actually means, and most importantly, how to fix it so you can get back to a smooth, lightning-fast IntelliJ experience. The core of the problem lies in how certain plugin actions update their presentation, specifically TemplateInsertAction#presentation@GoToAction from the com.fwdekker.randomness plugin, which took a whopping 418 milliseconds on the EDT. For those unfamiliar, the EDT is like the brain of your UI – it handles all user interactions and rendering. When an operation blocks it for hundreds of milliseconds, your application literally stops responding. We'll unpack why this happens and how a simple change to the AnAction.getActionUpdateThread property is the crucial step to resolving these IntelliJ Randomness Plugin UI freezes. Our goal is to make your IntelliJ IDEA not just functional, but exceptionally responsive by understanding and mitigating these performance bottlenecks.

Understanding the Culprit: The Event Dispatch Thread (EDT)

Alright, let's get down to the nitty-gritty: the Event Dispatch Thread (EDT). If you've ever done any Swing or AWT programming, or really any serious desktop UI work, you've probably heard of the EDT. For everyone else, think of the EDT as the sole conductor of your application's orchestra, specifically for anything related to the User Interface. It's a single, dedicated thread responsible for processing all UI events – clicks, key presses, mouse movements, and, crucially, updating what you see on the screen. Because it's a single thread, if any task running on the EDT takes too long, it essentially brings the entire UI to a grinding halt. This is why you experience those dreaded UI freezes and the feeling of a sluggish IntelliJ plugin experience. When the EDT is blocked, your application can't redraw its interface, can't process new input, and just looks like it's unresponsive, even if background tasks are still chugging along happily. This is a fundamental concept in responsive UI design: you never want to perform long-running or computationally intensive operations directly on the EDT.

Now, let's look at our specific issue. The report highlights that TemplateInsertAction#presentation is taking 418 ms to call on EDT. The presentation method of an AnAction (which is what TemplateInsertAction is) is responsible for determining how an action looks in the UI – its text, icon, and whether it's enabled or visible. Imagine every time you open a menu, this method is called. If it takes 418 milliseconds, that menu will take almost half a second to even appear or update correctly, causing a noticeable IntelliJ plugin lag. This is simply unacceptable for a smooth user experience. The stacktrace reveals that part of this slowdown comes from loading and rendering SVG icons via com.github.weisj.jsvg and com.intellij.ui.svg – a common pitfall if not handled carefully, as SVG parsing can be quite heavy. The AnAction.getActionUpdateThread property is a critical piece of the puzzle here. This property tells IntelliJ which thread should be used to run the update() method (which includes presentation) of an action. By default, or if incorrectly configured, it might run on the EDT. The fix often involves telling IntelliJ to run these potentially heavy update calls on a background thread (BGT) instead. This allows the UI to remain responsive while the plugin quietly prepares its action's presentation in the background. It's all about offloading work from that precious single UI thread to keep your IntelliJ snappy and performant, avoiding those annoying TemplateInsertAction related IntelliJ Randomness Plugin UI freezes.

The Randomness Plugin and Its Impact

So, let's zoom in on the specific hero (or sometimes, villain!) of our story: the com.fwdekker.randomness plugin, fondly known as the Randomness Plugin in IntelliJ. For many developers, this plugin is an absolute lifesaver, a true utility superstar. What does it do? It's designed to generate random data – think random numbers, strings, dates, names, even complex arrays or objects based on templates. This is incredibly useful for populating test data, creating mock APIs, or just quickly filling in placeholders during development. Imagine you need a list of 10 random emails or a complex JSON structure with random values; the Randomness Plugin can do that in a snap. It streamlines tasks that would otherwise be tedious and repetitive, boosting your productivity significantly. It's a fantastic tool, and that's precisely why encountering a performance hiccup like this can be so disruptive.

However, even the most helpful tools can sometimes have unintended side effects, and in this case, it's leading to Randomness Plugin issues that directly impact your user experience. The core of our problem, as identified in the report, stems from the TemplateInsertAction. This action is likely what you invoke when you want to insert a specific type of random data based on a predefined template. When you interact with this action – perhaps by opening a menu where it appears or searching for it – its presentation method is called. This method is supposed to quickly determine things like the action's name, its icon, and whether it should be enabled in the current context. The problem is, for this particular action, and possibly related to a specific template named com.fwdekker.randomness.insert.e9f618f1ce3e445489c5b671cdda1743.repeat.array, this presentation calculation is taking an unacceptable amount of time – 418 milliseconds, as we mentioned. This isn't just a minor delay; it's a significant plugin performance bottleneck that causes the IntelliJ Randomness Plugin UI freezes. Every time the UI needs to display or update this action, your entire IntelliJ IDEA window could become unresponsive for nearly half a second. This can lead to a very choppy and frustrating experience, especially if you're frequently interacting with menus or actions that trigger this particular TemplateInsertAction. It disrupts your flow, breaks your concentration, and ultimately makes an otherwise excellent plugin feel cumbersome. The issue highlights that even small, seemingly innocuous operations, when performed inefficiently on the EDT, can have a cascading negative impact on the overall responsiveness and usability of your development environment. This specific template insertion performance dip means users might feel like their IntelliJ is constantly struggling, even if it's just this one plugin causing the trouble.

Diagnosing the Lag: What the Stacktrace Tells Us

Alright, let's put on our detective hats and dissect that stacktrace analysis! For most users, a stacktrace looks like a daunting wall of technical jargon, but for developers, it's a treasure map pointing directly to the problem. Our stacktrace kicks off with a com.intellij.diagnostic.PluginException, which is IntelliJ's way of saying, "Hey, something went wrong with this plugin, and it's causing performance issues!" The most critical part here is the message: 418 ms to call on EDT TemplateInsertAction#presentation... Revise AnAction.getActionUpdateThread property. This immediately tells us two things: the TemplateInsertAction's presentation method is too slow, and it's running on the wrong thread – the EDT.

As we scroll through the lines, we see com.intellij.openapi.actionSystem.impl.ActionUpdaterKt.reportSlowEdtOperation, confirming that IntelliJ itself detected this slow operation on the Event Dispatch Thread. Then, computeOnEdt clearly indicates the action's update logic was indeed executed on the UI thread. But the real