alacritty: Performance regression

I just did a fresh build of Alacritty on macOS and noticed a massive performance regression. Whereas before everything was buttery smooth - after getting the latest commits things have slowed down terribly.

I can confirm that checking out 63787d0bf0bcf18422b97aa7f8dea2024948c176 and re-building fixes the issue, so the regression must’ve been introduced between 63787d0…HEAD.

These are the steps I used to build

$ git pull
Updating 63787d0..32dfddb
Fast-forward
 Cargo.lock          |   7 ++++++
 Cargo.toml          |   1 +
 README.md           |  10 ++++++++
 alacritty.yml       |  12 ++++++----
 alacritty_macos.yml |  12 ++++++----
 src/lib.rs          |   1 +
 src/renderer/mod.rs | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------
 7 files changed, 100 insertions(+), 58 deletions(-)

cargo build --release

make app

---

Here’s my system info

rustc 1.18.0

cargo 0.19.0-dev (28d1d60 2017-05-16)

                -/+:.           wayne@Waynes-MacBook-Pro.local
               :++++.           ------------------------------
              /+++/.            OS: macOS Sierra 10.12.5 16F73 x86_64
      .:-::- .+/:-``.::-        Model: MacBookPro13,3
   .:/++++++/::::/++++++/:`     Kernel: 16.6.0
 .:///////////////////////:`    Uptime: 1 day, 8 hours, 24 mins
 ////////////////////////`      Packages: 164
-+++++++++++++++++++++++`       Shell: zsh 5.3.1
/++++++++++++++++++++++/        Resolution: 1920x1200@2x
/sssssssssssssssssssssss.       DE: Aqua
:ssssssssssssssssssssssss-      WM: Quartz Compositor
 osssssssssssssssssssssssso/`   WM Theme: Blue
 `syyyyyyyyyyyyyyyyyyyyyyyy+`   Terminal: iTerm2
  `ossssssssssssssssssssss/     Terminal Font: Menlo-Regular 13
    :ooooooooooooooooooo+.      CPU: Intel i7-6700HQ (8) @ 2.60GHz
     `:+oo+/:-..-:/+o+/-        GPU: Intel HD Graphics 530, AMD Radeon Pro 450
                                Memory: 2550MiB / 16384MiB

# Configuration for Alacritty, the GPU enhanced terminal emulator

# Any items in the `env` entry below will be added as
# environment variables. Some entries may override variables
# set by alacritty it self.
env:
  # TERM env customization. Default is xterm-256color
  # Note: the default TERM value `xterm-256color` does not
  # specify all features alacritty supports. This does pose
  # a few issues with programs relying on terminfo and the
  # `tput` command
  TERM: xterm-256color

# Window dimensions in character columns and lines
# (changes require restart)
dimensions:
  columns: 160
  lines: 48

padding:
  x: 0
  y: 0

# The FreeType rasterizer needs to know the device DPI for best results
# (changes require restart)
dpi:
  x: 96.0
  y: 96.0

# Display tabs using this many cells (changes require restart)
tabspaces: 2

# When true, bold text is drawn using the bright variant of colors.
draw_bold_text_with_bright_colors: true

# Font configuration (changes require restart)
font:
  # The normal (roman) font face to use.
  normal:
    family: Meslo LG M DZ
    # Style can be specified to pick a specific face.
    # style: Regular

  # The bold font face
  bold:
    family: Meslo LG M DZ
    # Style can be specified to pick a specific face.
    # style: Bold

  # The italic font face
  italic:
    family: Meslo LG M DZ
    # Style can be specified to pick a specific face.
    # style: Italic

  # Point size of the font
  size: 13.0
  # Offset is the extra space around each character. offset.y can be thought of
  # as modifying the linespacing, and offset.x as modifying the letter spacing.
  offset:
    x: 0.0
    y: 0.0

  # OS X only: use thin stroke font rendering. Thin strokes are suitable
  # for retina displays, but for non-retina you probably want this set to
  # false.
  use_thin_strokes: true

# Should display the render timer
render_timer: false

# Use custom cursor colors. If true, display the cursor in the cursor.foreground
# and cursor.background colors, otherwise invert the colors of the cursor.
custom_cursor_colors: false

# Colors (Gruvbox dark)
colors:
  # Default colors
  primary:
    # hard contrast: background = '0x1d2021'
    background: '0x282828'
    # soft contrast: background = '0x32302f'
    foreground: '0xebdbb2'

  # Normal colors
  normal:
    black:   '0x282828'
    red:     '0xcc241d'
    green:   '0x98971a'
    yellow:  '0xd79921'
    blue:    '0x458588'
    magenta: '0xb16286'
    cyan:    '0x689d6a'
    white:   '0xa89984'

  # Bright colors
  bright:
    black:   '0x928374'
    red:     '0xfb4934'
    green:   '0xb8bb26'
    yellow:  '0xfabd2f'
    blue:    '0x83a598'
    magenta: '0xd3869b'
    cyan:    '0x8ec07c'
    white:   '0xebdbb2'

# Visual Bell
#
# Any time the BEL code is received, Alacritty "rings" the visual bell. Once
# rung, the terminal background will be set to white and transition back to the
# default background color. You can control the rate of this transition by
# setting the `duration` property (represented in milliseconds). You can also
# configure the transition function by setting the `animation` property.
#
# Possible values for `animation`
# `Ease`
# `EaseOut`
# `EaseOutSine`
# `EaseOutQuad`
# `EaseOutCubic`
# `EaseOutQuart`
# `EaseOutQuint`
# `EaseOutExpo`
# `EaseOutCirc`
# `Linear`
#
# To completely disable the visual bell, set its duration to 0.
#
visual_bell:
  animation: EaseOutExpo
  duration: 0

# Key bindings
#
# Each binding is defined as an object with some properties. Most of the
# properties are optional. All of the alphabetical keys should have a letter for
# the `key` value such as `V`. Function keys are probably what you would expect
# as well (F1, F2, ..). The number keys above the main keyboard are encoded as
# `Key1`, `Key2`, etc. Keys on the number pad are encoded `Number1`, `Number2`,
# etc.  These all match the glutin::VirtualKeyCode variants.
#
# Possible values for `mods`
# `Command`, `Super` refer to the super/command/windows key
# `Control` for the control key
# `Shift` for the Shift key
# `Alt` and `Option` refer to alt/option
#
# mods may be combined with a `|`. For example, requiring control and shift
# looks like:
#
# mods: Control|Shift
#
# The parser is currently quite sensitive to whitespace and capitalization -
# capitalization must match exactly, and piped items must not have whitespace
# around them.
#
# Either an `action` or `chars` field must be present. `chars` writes the
# specified string every time that binding is activated. These should generally
# be escape sequences, but they can be configured to send arbitrary strings of
# bytes. Possible values of `action` include `Paste` and `PasteSelection`.
key_bindings:
  # Defaults
  - { key: V,        mods: Command, action: Paste                        }
  - { key: C,        mods: Command, action: Copy                         }
  - { key: Q,        mods: Command, action: Quit                         }
  - { key: W,        mods: Command, action: Quit                         }
  - { key: Home,                    chars: "\x1bOH",   mode: AppCursor   }
  - { key: Home,                    chars: "\x1b[1~",  mode: ~AppCursor  }
  - { key: End,                     chars: "\x1bOF",   mode: AppCursor   }
  - { key: End,                     chars: "\x1b[4~",  mode: ~AppCursor  }
  - { key: PageUp,                  chars: "\x1b[5~"                     }
  - { key: PageDown,                chars: "\x1b[6~"                     }
  - { key: Left,     mods: Shift,   chars: "\x1b[1;2D"                   }
  - { key: Left,     mods: Control, chars: "\x1b[1;5D"                   }
  - { key: Left,     mods: Alt,     chars: "\x1b[1;3D"                   }
  - { key: Left,                    chars: "\x1b[D",   mode: ~AppCursor  }
  - { key: Left,                    chars: "\x1bOD",   mode: AppCursor   }
  - { key: Right,    mods: Shift,   chars: "\x1b[1;2C"                   }
  - { key: Right,    mods: Control, chars: "\x1b[1;5C"                   }
  - { key: Right,    mods: Alt,     chars: "\x1b[1;3C"                   }
  - { key: Right,                   chars: "\x1b[C",   mode: ~AppCursor  }
  - { key: Right,                   chars: "\x1bOC",   mode: AppCursor   }
  - { key: Up,       mods: Shift,   chars: "\x1b[1;2A"                   }
  - { key: Up,       mods: Control, chars: "\x1b[1;5A"                   }
  - { key: Up,       mods: Alt,     chars: "\x1b[1;3A"                   }
  - { key: Up,                      chars: "\x1b[A",   mode: ~AppCursor  }
  - { key: Up,                      chars: "\x1bOA",   mode: AppCursor   }
  - { key: Down,     mods: Shift,   chars: "\x1b[1;2B"                   }
  - { key: Down,     mods: Control, chars: "\x1b[1;5B"                   }
  - { key: Down,     mods: Alt,     chars: "\x1b[1;3B"                   }
  - { key: Down,                    chars: "\x1b[B",   mode: ~AppCursor  }
  - { key: Down,                    chars: "\x1bOB",   mode: AppCursor   }
  - { key: Tab,      mods: Shift,   chars: "\x1b[Z"                      }
  - { key: F1,                      chars: "\x1bOP"                      }
  - { key: F2,                      chars: "\x1bOQ"                      }
  - { key: F3,                      chars: "\x1bOR"                      }
  - { key: F4,                      chars: "\x1bOS"                      }
  - { key: F5,                      chars: "\x1b[15~"                    }
  - { key: F6,                      chars: "\x1b[17~"                    }
  - { key: F7,                      chars: "\x1b[18~"                    }
  - { key: F8,                      chars: "\x1b[19~"                    }
  - { key: F9,                      chars: "\x1b[20~"                    }
  - { key: F10,                     chars: "\x1b[21~"                    }
  - { key: F11,                     chars: "\x1b[23~"                    }
  - { key: F12,                     chars: "\x1b[24~"                    }
  - { key: Back,                    chars: "\x7f"                        }
  - { key: Back,     mods: Alt,     chars: "\x1b\x7f"                    }
  - { key: Insert,                  chars: "\x1b[2~"                     }
  - { key: Delete,                  chars: "\x1b[3~",  mode: AppKeypad   }
  - { key: Delete,                  chars: "\x1b[P",   mode: ~AppKeypad  }
  # Custom
  - { key: H,        mods: Alt,     chars: "\x1bh"                       }
  - { key: J,        mods: Alt,     chars: "\x1bj"                       }
  - { key: K,        mods: Alt,     chars: "\x1bk"                       }
  - { key: L,        mods: Alt,     chars: "\x1bl"                       }


# Mouse bindings
#
# Currently doesn't support modifiers. Both the `mouse` and `action` fields must
# be specified.
#
# Values for `mouse`:
# - Middle
# - Left
# - Right
# - Numeric identifier such as `5`
#
# Values for `action`:
# - Paste
# - PasteSelection
# - Copy (TODO)
mouse_bindings:
  - { mouse: Middle, action: PasteSelection }

mouse:
  double_click: { threshold: 300 }
  triple_click: { threshold: 300 }

selection:
  semantic_escape_chars: ",│`|:\"' ()[]{}<>"

hide_cursor_when_typing: false

# Shell
#
# You can set shell.program to the path of your favorite shell, e.g. /bin/fish.
# Entries in shell.args are passed unmodified as arguments to the shell.
#
shell:
  program: /usr/local/bin/zsh
#  args:
#    - --login