Default Thread settings (threads=true) cause bad performance on CPU about tullio.jl HOT 3 CLOSED

julia> @btime Zygote.gradient(f, x)[1];
  9.570 ms (163 allocations: 30.53 MiB)

julia> @btime Zygote.gradient(ft, x)[1];
  13.836 ms (26 allocations: 30.52 MiB)

# forward only
julia> @btime f($x);
  949.564 μs (92 allocations: 6.03 KiB)

julia> @btime ft($x);
  1.825 ms (0 allocations: 0 bytes)

using Zygote, Tullio, BenchmarkTools
x = abs.(randn((500, 500)));
f(x) = (@tullio y =  abs2(x[i+1, j] - x[i-1, j]) + abs2(x[i, j+1] - x[i, j-1]))
ft(x) = (@tullio threads=false y = abs2(x[i+1, j] - x[i-1, j]) + abs2(x[i, j+1] - x[i, j-1]))

@btime f($x);
@btime ft($x); 

@btime Zygote.gradient($f, $x)[1];
@btime Zygote.gradient($ft, $x)[1];

using Zygote, Tullio, BenchmarkTools, ImageView
x = abs.(randn((500, 500)));
f(x) = (@tullio y =  abs2(x[i+1, j] - x[i-1, j]) + abs2(x[i, j+1] - x[i, j-1]))
ft(x) = (@tullio threads=false y = abs2(x[i+1, j] - x[i-1, j]) + abs2(x[i, j+1] - x[i, j-1]))

@btime f($x);
@btime ft($x); 

@btime Zygote.gradient($f, $x)[1];
@btime Zygote.gradient($ft, $x)[1];