linecharView 数据源多了之后 marker 的显示 滑动跟随手势移动都会卡

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## What did you do?

linecharView数据源多了之后marker的显示滑动跟随手势移动都会卡 ，但是在安卓上就不会出现这样的问题

## What did you expect to happen?

希望在数据很多的时候再上千上万的时候，不会出现卡顿
## What happened instead?

## Charts Environment

**Charts version/Branch/Commit Number:**
**Xcode version:11
**Swift version:4
**Platform(s) running Charts:**
**macOS version running Xcode:

## Demo Project

ℹ Please link to or upload a project we can download that reproduces the issue.