Significant lag before cards are rendered

[milnivlek]

I just added a few more vertical-stack-in-card cards to my dashboard, and for some reason they usually take multiple seconds to render. This makes the UI extremely janky. Any ideas what I'm doing wrong? I've uploaded a screen recording here:

vertical-stack-in-card-lag.mp4

Here's the corresponding dashboard YAML. I extracted this from my full dashboard as a (relatively) minimal example to demonstrate the problem. This lag doesn't happen 100% of the time, but it seems to trigger especially often when switching from another dashboard to this one.

views:
  - title: Test
    cards:
      - type: custom:vertical-stack-in-card
        cards:
          - type: custom:layout-card
            layout_type: custom:grid-layout
            layout:
              grid-template-columns: 59px auto
              grid-template-rows: auto
            cards:
              - type: custom:mushroom-template-card
                primary: ''
                secondary: ''
                icon: mdi:television-classic
                fill_container: false
                tap_action:
                  action: none
                card_mod:
                  style: |-
                    ha-card {
                      border: 0;
                      margin-left: 0;
                      padding-left: 4px !important;
                    }
              - type: custom:stack-in-card
                cards:
                  - type: horizontal-stack
                    cards:
                      - type: custom:mushroom-template-card
                        primary: Living Room TV Power Toggle
                        fill_container: true
                        badge_icon: ''
                        icon: ''
                        card_mod:
                          style: |-
                            ha-card {
                              min-height: 50px;
                              text-align: center;
                            }
                  - type: custom:vertical-stack-in-card
                    cards:
                      - type: custom:layout-card
                        layout_type: custom:grid-layout
                        layout:
                          margin: 0
                          padding: 0
                          grid-template-columns: 90px auto
                          grid-template-rows: auto
                        cards:
                          - type: custom:mushroom-template-card
                            primary: 'Source:'
                            secondary: ''
                            fill_container: false
                            tap_action:
                              action: none
                            card_mod:
                              style: |-
                                ha-card {
                                  border: 0;
                                  margin-left: 0;
                                  padding-top: 9px;
                                  padding-left: 0px !important;
                                }
                          - type: horizontal-stack
                            cards:
                              - type: custom:mushroom-template-card
                                icon: mdi:music
                                fill_container: true
                                card_mod:
                                  style: |-
                                    ha-card {
                                      border: 0;
                                      text-align: center;
                                    }
                              - type: custom:mushroom-template-card
                                icon: mdi:television-box
                                fill_container: true
                                card_mod:
                                  style: |-
                                    ha-card {
                                      border: 0;
                                      text-align: center;
                                    }
                              - type: custom:mushroom-template-card
                                icon: mdi:laptop
                                fill_container: true
                                card_mod:
                                  style: |-
                                    ha-card {
                                      border: 0;
                                      text-align: center;
                                    }
                  - type: custom:vertical-stack-in-card
                    cards:
                      - type: custom:layout-card
                        layout_type: custom:grid-layout
                        layout:
                          margin: 0
                          padding: 0
                          grid-template-columns: 90px auto
                          grid-template-rows: auto
                        cards:
                          - type: custom:mushroom-template-card
                            primary: 'Volume:'
                            secondary: ''
                            fill_container: false
                            card_mod:
                              style: |-
                                ha-card {
                                  border: 0;
                                  margin-left: 0;
                                  min-height: 40px;
                                  padding-top: 9px;
                                  padding-left: 0px !important;
                                }
                          - type: horizontal-stack
                            cards:
                              - type: custom:mushroom-template-card
                                icon: mdi:minus-thick
                                fill_container: true
                                card_mod:
                                  style: |-
                                    ha-card {
                                      border: 0;
                                      text-align: center;
                                    }
                              - type: custom:mushroom-template-card
                                icon: mdi:plus-thick
                                fill_container: true
                                card_mod:
                                  style: |-
                                    ha-card {
                                      border: 0;
                                      text-align: center;
                                    }