With Fira Code Medium font, it seems to me that letters are a way smoother when opening the document in gnome-terminal and console neovim than with neovim-gtk. See the screenshot below
Left is neovim-gtk and right is the console neovim in gnome-terminal. Using RHEL-7 with gtk3-3.22.26-3.el7.x86_64, freetype-2.4.11-15.el7.x86_64, pango-1.40.4-1.el7.x86_64, and neovim-0.2.2-1.0.8.gitd49c1dda8.el7.centos.x86_64. neovim-gtk is my own build from commit 25921d2.
With Fira Code Medium font, it seems to me that letters are a way smoother when opening the document in gnome-terminal and console neovim than with neovim-gtk. See the screenshot below
Left is neovim-gtk and right is the console neovim in gnome-terminal. Using RHEL-7 with gtk3-3.22.26-3.el7.x86_64, freetype-2.4.11-15.el7.x86_64, pango-1.40.4-1.el7.x86_64, and neovim-0.2.2-1.0.8.gitd49c1dda8.el7.centos.x86_64. neovim-gtk is my own build from commit 25921d2.