记录下 MarkdownView 的性能优化

我的开源项目 MarkdownView 的 0.2.0 版本 终于发布了！

改版本带来了性能上的巨大进步：

Performance

• Rendering is now at least 3x faster on ALL DEVICES.
• Real-time previewing is now much much smoother.
• Scrolling is much quicker and smoother with no frame drop.
• Memory usage has been reduced by 30%

借此机会，记录下我的优化思路。