iOS Large Client Performance Optimization: Reducing Startup Time from 2.41 s to 1.09 s

Overview

This article introduces the iOS large‑client performance optimization process and its outcomes. Before optimization, the client started in 2–3 seconds, but 80 % of users needed about 6 seconds from tapping the icon to see the home page, while a competitor’s app started in ~0.5 seconds and reached the home page in ~3.6 seconds. After optimization, internal testing showed our startup time was no slower than the competitor’s, with 80 % of users improving from 2.41 seconds to 1.09 seconds, and home‑page display time dropping from 5.91 seconds to 3.89 seconds.

Optimization Process

The first step was to add instrumentation to collect precise launch metrics. We added measurements for total startup time, IM component load time, and WeChat load time. The collected data revealed that 80 % of users required about 6 seconds to see the home page.

We then benchmarked against the competitor using the same device and environment, confirming the performance gap.

After identifying the gap, we performed code walkthroughs and analyzed instrumentation data, pinpointing four main issue areas:

1) Network Dependency and Timeout Settings

A certain component was loaded on the main thread with a 10‑second timeout.

2) Timed Processing

• Brand advertisement page had a fixed duration. • Splash screen advertisement displayed for a fixed duration. • Splash advertisement disappearance animation had a fixed duration.

3) Code Logic

• Unused business code remained in the project. • Business tasks that could be delayed or lazy‑loaded were executed during startup. • Unnecessary functions of third‑party SDKs were left enabled. • Home entry count increased, adding significant load without high‑performance implementation.

Home entry count growth contributed heavily to the performance regression.

Optimization Results

The first phase of optimization has been released. 80 % of users now experience a startup time reduced from 2.41 seconds to 1.09 seconds, and the home page appears in 3.89 seconds instead of 5.91 seconds. This phase focused on optimizing load timing, removing unnecessary logic, and improving code implementation. Detailed metrics are shown below.