Environment

Binaries:

• Node: 13.7.0 - ~/.nvm/versions/node/v13.7.0/bin/node
• Yarn: 1.21.1 - /usr/local/bin/yarn
• npm: 6.13.6 - ~/.nvm/versions/node/v13.7.0/bin/npm

npmPackages:

• babel-plugin-styled-components: ^1.10.7 => 1.10.6
• styled-components: ^5.0.1 => 5.0.1

Problem

We are using styled-components and Next.js (7.2.1) and we have experienced memory leaks in our app for some time, so I started to investigate it, in the process I found other issues here about:

• using the css helper when composing styling partials to be interpolated into a styled component
• not to use @import inside createGlobalStyle
• not dynamically create components

So I went through the whole app making sure to avoid these. I deployed a new version but the memory leak was still present. As seen on the graph below:

After inspecting the node server I found out it was createGlobalStyle in our _app.js (Next.js file) that caused the memory to rise. In the createGlobalStyle we used fontFace/normalize from polished), and around 50 other lines of reset css (nothing special).

Removing createGlobalStyle solved the memory leak (or at least reduced to a minimum).
See the graph below:

Did we use createGlobalStylewrong or do someone have some insight to this?