Make Webpack faster

[AwesomestCode]

We're at this point again. Somehow, webpack is again being extremely slow. This is hampering development; I can't iterate quickly/test stuff if I need to wait a minute every time I make a change, no matter how small.

[Saiv46]

What speed-measure-webpack-plugin gives to me

 SMP  ⏱  
General output time took 3 mins, 18.8 secs   

 SMP  ⏱  Plugins
CopyPlugin took 1 min, 7.67 secs
GenerateSW took 9.23 secs
NormalModuleReplacementPlugin took 0.898 secs
HtmlWebpackPlugin took 0.067 secs
ProvidePlugin took 0.001 secs

 SMP  ⏱  Loaders
modules with no loaders took 25.062 secs     
  module count = 1061
html-webpack-plugin took 0.13 secs
  module count = 1

Looks like much time are wasted on I/O, copying files every time.

[Karang]

Indeed, it looks likes it's copying a bunch of useless stuff too. https://github.com/PrismarineJS/prismarine-web-client/blob/master/webpack.common.js#L72 also copy sub-directories while we are only interested in the .png at the root (and maybe some entities and gui textures, but we clearly don't need the many many individual files of the blocks).

[AwesomestCode]

Does it copy the files for dev builds though? I thought those were incremental

[Saiv46]

So, I wrote a little plugin for symlinking directories, now dev builds are faster

 SMP  ⏱
General output time took 57.3 secs

 SMP  ⏱  Plugins
GenerateSW took 14.13 secs
NormalModuleReplacementPlugin took 0.388 secs
HtmlWebpackPlugin took 0.097 secs
SymlinkPlugin took 0.088 secs
CopyPlugin took 0.078 secs
ProvidePlugin took 0.001 secs

 SMP  ⏱  Loaders
modules with no loaders took 15.38 secs
  module count = 703
html-webpack-plugin took 0.043 secs
  module count = 1

[AwesomestCode]

#227 was reverted so we're back at square 1

[rom1504]

yep, I reverted because it broke npm start