Changing the grid cell border color

[chunyukuo88]

I need to have the grid cells have a specific border color at all times. The way I find was to add the theme attribute and pass it a style object thusly:

<DataEditor
  theme={{ borderColor: 'green' }}  
/>

This successfully changed the color of each cell's border; however, it made the grid very, very slow. Is this a known bug, or am I doing it wrong? I tried editing the object that gets passed to getCellContent but I couldn't find any fields that affected border color.