This Hacker News discussion revolves around performance optimization, particularly within the context of UI development, and explores various strategies and trade-offs. The core themes include:
Lazy Loading and Conditional Rendering
A significant portion of the discussion centers on the idea of deferring the rendering of UI components until they are actually needed, rather than having them initialized upfront. This is seen as a direct way to improve performance, especially in applications with many potentially unused elements.
- The initial comment highlights this strategy: "Rendering the UI (not downloading the code, this is still part of the bundle) only when you need it seems to be a low hanging fruit for optimizing performance."
- This approach is contrasted with having components "idle waiting for activation."
Efficient Component Instantiation and Management
Related to lazy loading, participants discuss how to manage the creation and lifecycle of components like modals and tooltips to avoid unnecessary overhead.
- In the Blazor context, a specific pattern is mentioned: "In the Blazor space we use factories/managers to spawn new instances of a modal/tooltip instead of having something idle waiting for activation."
- Another suggestion proposes a global management system: "You basically have a global part of the component and a local part. The global part is what actually gets rendered when necessary and manages current state, the local part defines what content will be rendered inside the global part for a particular trigger."
- A more conservative approach is also suggested: "At most one instance at start up. Asynchronous creation or lazy creation on first use are two other potential options."
Profiling Beyond Basic Runtime Analysis
The discussion emphasizes that effective performance optimization requires looking beyond simple runtime measurements and considering other factors, such as invocation counts.
- A key point is made about the limitations of basic profiling: "Looking at flame charts is only step one. You also need to look at invocation counts, for things that seem to be getting called far more often than they should be."
- The reason for this deeper analysis is also explained: "Profiling tools frequently (dare I say consistently) misattribute costs of functions due to pressures on the CPU subsystems. And most of the times I’ve found optimizations that were substantially larger improvements than expected, it’s been from cumulative call count, not run time."
Trade-offs of Optimization Strategies
While various optimization techniques are discussed, there's an acknowledgment that these strategies often come with their own sets of trade-offs.
- A trade-off with deferred instantiation is noted: "The tradeoff is for more complicated components, first renders can be slower."
- A user also points out a potential issue with a specific implementation of lazy loading: "That breaks the out transition."
- However, another user finds this acceptable, prioritizing speed over animations: "So, win-win? I want a modal to get out of the way as fast as possible, any fade/transition animations are keeping me from what I want to look at. :)"
The Importance of Continuous Auditing and Cost of Accrual
The conversation touches upon the long-term maintenance of software and how accumulated inefficiencies can silently degrade performance, necessitating ongoing audits.
- A general principle is stated: "Any time a library in your code goes from being used by a couple people to used by everyone, you have to periodically audit it from then on."
- A real-world example illustrates this: "A set of libraries on our code had hit 20% of response time through years of accretion. A couple months to cut that in half, no architectural or cache changes. Just about the largest and definitely the most cost effective initiative we completed on that team."
Comparisons to Immediate Mode GUI (IMGUI)
Immediate Mode GUI approaches are brought up as an interesting point of comparison, with some inherent performance advantages due to their on-demand rendering nature.
- A user notes: "This is one scenario where IMGUI approaches have a small win, even if it's by accident - since GUI elements are constructed on demand in immediate mode, invisible/unused elements won't have tooltip setup run, and the tooltip setup code will probably only run for the control that's showing a tooltip."
Questioning Architectural Choices
At least one user questions the fundamental design decisions that led to the performance issues, specifically concerning the implementation of tooltips.
- Curiosity about a specific design choice is expressed: "It's interesting that every control previously had its own dedicated tooltip component, instead of having all controls share a single system wide tooltip. I'm curious why they designed it that way."
Startup Time Impact and Metrics
The discussion highlights the significant impact of inefficient UI patterns on application startup time, with specific numerical estimates provided.
- A user calculates potential startup time savings based on figures from the article: "It does give a 0.05ms per tooltip figure, so I guess multiplied by 38000 gives ~2s saved, which is not too bad."
- Directly quoted figures from the article illustrate the problem: "\"Together, these two problems can result in the editor spending an extremely long time just creating unused tooltips. In a debug build of the engine, creating all of these tooltips resulted in 2-5 seconds of startup time. In comparison development builds were faster, taking just under a second.\""
Perceived Bloat and User Experience in Large Engines
A segment of the discussion expresses frustration with the perceived bloat and performance issues in large development environments like Unreal Engine, drawing parallels to web development.
- A strong opinion is voiced: "It's no wonder UE5 games have the reputation of being poorly optimized, you need an insane machine only just to run the editor.. State of the art graphics pipeline, but webdev level of bloat when it comes to software.. I'd even argue electron is a smoother experience tan Unreal Engine Editor Insanity"
- This sentiment is reinforced by a personal anecdote about asset management in Unreal Engine: "I once made the mistake to buy some sound effects from Fab, I had to download the entire Unreal Engine and start it to create a project to then import the assets.. It took the whole afternoon"