First command is slow after loading Plots.jl

Hi all-

I have noticed a long lag (approximately 3-5 seconds) for the first command after entering using Plots. The timing below is misleading because Julia continues to run after printing.

julia> using Plots

julia> @time x = 1
  0.000001 seconds (4 allocations: 192 bytes)

I tried to reproduce this behavior by loading other packages, but have not yet been successful. Does anyone know why this occurs?

Info: Ubuntu 16.04, Julia .7, [91a5bcdd] Plots v0.19.3

After updating to 1.0 from .7, I was unable to reproduce this behavior. So it appears to be specific to .7.