diff --git a/lua/nvim-tree/actions/moves/item.lua b/lua/nvim-tree/actions/moves/item.lua
index 9375ef5f4dc..bf72c0ea2df 100644
--- a/lua/nvim-tree/actions/moves/item.lua
+++ b/lua/nvim-tree/actions/moves/item.lua
@@ -3,6 +3,7 @@ local view = require "nvim-tree.view"
 local core = require "nvim-tree.core"
 local lib = require "nvim-tree.lib"
 local explorer_node = require "nvim-tree.explorer.node"
+local diagnostics = require "nvim-tree.diagnostics"
 
 local M = {}
 
@@ -33,7 +34,8 @@ function M.fn(opts)
         local git_status = explorer_node.get_git_status(node)
         valid = git_status ~= nil and (not opts.skip_gitignored or git_status[1] ~= "!!")
       elseif opts.what == "diag" then
-        valid = node.diag_status ~= nil
+        local diag_status = diagnostics.get_diag_status(node)
+        valid = diag_status ~= nil and diag_status.value ~= nil
       elseif opts.what == "opened" then
         valid = vim.fn.bufloaded(node.absolute_path) ~= 0
       end
diff --git a/lua/nvim-tree/diagnostics.lua b/lua/nvim-tree/diagnostics.lua
index 93c689634a9..6ca13c9c067 100644
--- a/lua/nvim-tree/diagnostics.lua
+++ b/lua/nvim-tree/diagnostics.lua
@@ -1,18 +1,44 @@
 local utils = require "nvim-tree.utils"
 local view = require "nvim-tree.view"
-local core = require "nvim-tree.core"
 local log = require "nvim-tree.log"
 
 local M = {}
 
-local severity_levels = {
+---TODO add "$VIMRUNTIME" to "workspace.library" and use the @enum instead of this integer
+---@alias lsp.DiagnosticSeverity integer
+
+---COC severity level strings to LSP severity levels
+---@enum COC_SEVERITY_LEVELS
+local COC_SEVERITY_LEVELS = {
   Error = 1,
   Warning = 2,
   Information = 3,
   Hint = 4,
 }
 
----@return table
+---Absolute Node path to LSP severity level
+---@alias NodeSeverities table<string, lsp.DiagnosticSeverity>
+
+---@class DiagStatus
+---@field value lsp.DiagnosticSeverity|nil
+---@field cache_version integer
+
+--- The buffer-severity mappings derived during the last diagnostic list update.
+---@type NodeSeverities
+local NODE_SEVERITIES = {}
+
+---The cache version number of the buffer-severity mappings.
+---@type integer
+local NODE_SEVERITIES_VERSION = 0
+
+---@param path string
+---@return string
+local function uniformize_path(path)
+  return utils.canonical_path(path:gsub("\\", "/"))
+end
+
+---Marshal severities from LSP. Does nothing when LSP disabled.
+---@return NodeSeverities
 local function from_nvim_lsp()
   local buffer_severity = {}
 
@@ -25,11 +51,10 @@ local function from_nvim_lsp()
     for _, diagnostic in ipairs(vim.diagnostic.get(nil, { severity = M.severity })) do
       local buf = diagnostic.bufnr
       if vim.api.nvim_buf_is_valid(buf) then
-        local bufname = vim.api.nvim_buf_get_name(buf)
-        local lowest_severity = buffer_severity[bufname]
-        if not lowest_severity or diagnostic.severity < lowest_severity then
-          buffer_severity[bufname] = diagnostic.severity
-        end
+        local bufname = uniformize_path(vim.api.nvim_buf_get_name(buf))
+        local severity = diagnostic.severity
+        local highest_severity = buffer_severity[bufname] or severity
+        buffer_severity[bufname] = math.min(highest_severity, severity)
       end
     end
   end
@@ -37,91 +62,148 @@ local function from_nvim_lsp()
   return buffer_severity
 end
 
----@param severity integer
+---Severity is within diagnostics.severity.min, diagnostics.severity.max
+---@param severity lsp.DiagnosticSeverity
 ---@param config table
 ---@return boolean
 local function is_severity_in_range(severity, config)
   return config.max <= severity and severity <= config.min
 end
 
----@return table
-local function from_coc()
-  if vim.g.coc_service_initialized ~= 1 then
-    return {}
+---Handle any COC exceptions, preventing any propagation
+---@param err string
+local function handle_coc_exception(err)
+  log.line("diagnostics", "handle_coc_exception: %s", vim.inspect(err))
+  local notify = true
+
+  -- avoid distractions on interrupts (CTRL-C)
+  if err:find "Vim:Interrupt" or err:find "Keyboard interrupt" then
+    notify = false
   end
 
-  local diagnostic_list = vim.fn.CocAction "diagnosticList"
-  if type(diagnostic_list) ~= "table" or vim.tbl_isempty(diagnostic_list) then
-    return {}
+  if notify then
+    require("nvim-tree.notify").error("Diagnostics update from coc.nvim failed. " .. vim.inspect(err))
   end
+end
 
-  local diagnostics = {}
-  for _, diagnostic in ipairs(diagnostic_list) do
-    local bufname = diagnostic.file
-    local coc_severity = severity_levels[diagnostic.severity]
+---COC service initialized
+---@return boolean
+local function is_using_coc()
+  return vim.g.coc_service_initialized == 1
+end
 
-    local serverity = diagnostics[bufname] or vim.diagnostic.severity.HINT
-    diagnostics[bufname] = math.min(coc_severity, serverity)
+---Marshal severities from COC. Does nothing when COC service not started.
+---@return NodeSeverities
+local function from_coc()
+  if not is_using_coc() then
+    return {}
+  end
+
+  local ok, diagnostic_list = xpcall(function()
+    return vim.fn.CocAction "diagnosticList"
+  end, handle_coc_exception)
+  if not ok or type(diagnostic_list) ~= "table" or vim.tbl_isempty(diagnostic_list) then
+    return {}
   end
 
   local buffer_severity = {}
-  for bufname, severity in pairs(diagnostics) do
-    if is_severity_in_range(severity, M.severity) then
-      buffer_severity[bufname] = severity
+  for _, diagnostic in ipairs(diagnostic_list) do
+    local bufname = uniformize_path(diagnostic.file)
+    local coc_severity = COC_SEVERITY_LEVELS[diagnostic.severity]
+    local highest_severity = buffer_severity[bufname] or coc_severity
+    if is_severity_in_range(highest_severity, M.severity) then
+      buffer_severity[bufname] = math.min(highest_severity, coc_severity)
     end
   end
 
   return buffer_severity
 end
 
-local function is_using_coc()
-  return vim.g.coc_service_initialized == 1
+---Maybe retrieve severity level from the cache
+---@param node Node
+---@return DiagStatus
+local function from_cache(node)
+  local nodepath = uniformize_path(node.absolute_path)
+  local max_severity = nil
+  if not node.nodes then
+    -- direct cache hit for files
+    max_severity = NODE_SEVERITIES[nodepath]
+  else
+    -- dirs should be searched in the list of cached buffer names by prefix
+    for bufname, severity in pairs(NODE_SEVERITIES) do
+      local node_contains_buf = vim.startswith(bufname, nodepath .. "/")
+      if node_contains_buf then
+        if severity == M.severity.max then
+          max_severity = severity
+          break
+        else
+          max_severity = math.min(max_severity or severity, severity)
+        end
+      end
+    end
+  end
+  return { value = max_severity, cache_version = NODE_SEVERITIES_VERSION }
 end
 
+---Fired on DiagnosticChanged and CocDiagnosticChanged events:
+---debounced retrieval, cache update, version increment and draw
 function M.update()
-  if not M.enable or not core.get_explorer() or not view.is_buf_valid(view.get_bufnr()) then
+  if not M.enable then
     return
   end
   utils.debounce("diagnostics", M.debounce_delay, function()
     local profile = log.profile_start "diagnostics update"
-    log.line("diagnostics", "update")
-
-    local buffer_severity
     if is_using_coc() then
-      buffer_severity = from_coc()
+      NODE_SEVERITIES = from_coc()
     else
-      buffer_severity = from_nvim_lsp()
-    end
-
-    local nodes_by_line = utils.get_nodes_by_line(core.get_explorer().nodes, core.get_nodes_starting_line())
-    for _, node in pairs(nodes_by_line) do
-      node.diag_status = nil
+      NODE_SEVERITIES = from_nvim_lsp()
     end
-
-    for bufname, severity in pairs(buffer_severity) do
-      local bufpath = utils.canonical_path(bufname)
-      log.line("diagnostics", " bufpath '%s' severity %d", bufpath, severity)
-      if 0 < severity and severity < 5 then
-        for line, node in pairs(nodes_by_line) do
-          local nodepath = utils.canonical_path(node.absolute_path)
-          log.line("diagnostics", "  %d checking nodepath '%s'", line, nodepath)
-
-          local node_contains_buf = vim.startswith(bufpath:gsub("\\", "/"), nodepath:gsub("\\", "/") .. "/")
-          if M.show_on_dirs and node_contains_buf and (not node.open or M.show_on_open_dirs) then
-            log.line("diagnostics", " matched fold node '%s'", node.absolute_path)
-            node.diag_status = severity
-          elseif nodepath == bufpath then
-            log.line("diagnostics", " matched file node '%s'", node.absolute_path)
-            node.diag_status = severity
-          end
-        end
+    NODE_SEVERITIES_VERSION = NODE_SEVERITIES_VERSION + 1
+    if log.enabled "diagnostics" then
+      for bufname, severity in pairs(NODE_SEVERITIES) do
+        log.line("diagnostics", "Indexing bufname '%s' with severity %d", bufname, severity)
       end
     end
     log.profile_end(profile)
-    require("nvim-tree.renderer").draw()
+    if view.is_buf_valid(view.get_bufnr()) then
+      require("nvim-tree.renderer").draw()
+    end
   end)
 end
 
+---Maybe retrieve diagnostic status for a node.
+---Returns cached value when node's version matches.
+---@param node Node
+---@return DiagStatus|nil
+function M.get_diag_status(node)
+  if not M.enable then
+    return nil
+  end
+
+  -- dir but we shouldn't show on dirs at all
+  if node.nodes ~= nil and not M.show_on_dirs then
+    return nil
+  end
+
+  -- here, we do a lazy update of the diagnostic status carried by the node.
+  -- This is by design, as diagnostics and nodes live in completely separate
+  -- worlds, and this module is the link between the two
+  if not node.diag_status or node.diag_status.cache_version < NODE_SEVERITIES_VERSION then
+    node.diag_status = from_cache(node)
+  end
+
+  -- file
+  if not node.nodes then
+    return node.diag_status
+  end
+
+  -- dir is closed or we should show on open_dirs
+  if not node.open or M.show_on_open_dirs then
+    return node.diag_status
+  end
+  return nil
+end
+
 function M.setup(opts)
   M.enable = opts.diagnostics.enable
   M.debounce_delay = opts.diagnostics.debounce_delay
diff --git a/lua/nvim-tree/node.lua b/lua/nvim-tree/node.lua
index 55ee1942dc4..323fc53c4c4 100644
--- a/lua/nvim-tree/node.lua
+++ b/lua/nvim-tree/node.lua
@@ -17,6 +17,7 @@
 ---@field parent DirNode
 ---@field type string
 ---@field watcher function|nil
+---@field diag_status DiagStatus|nil
 
 ---@class DirNode: BaseNode
 ---@field has_children boolean
diff --git a/lua/nvim-tree/renderer/components/diagnostics.lua b/lua/nvim-tree/renderer/components/diagnostics.lua
index 3a145406e70..1fa864deac9 100644
--- a/lua/nvim-tree/renderer/components/diagnostics.lua
+++ b/lua/nvim-tree/renderer/components/diagnostics.lua
@@ -1,4 +1,5 @@
 local HL_POSITION = require("nvim-tree.enum").HL_POSITION
+local diagnostics = require "nvim-tree.diagnostics"
 
 local M = {
   HS_FILE = {},
@@ -17,10 +18,11 @@ function M.get_highlight(node)
   end
 
   local group
+  local diag_status = diagnostics.get_diag_status(node)
   if node.nodes then
-    group = M.HS_FOLDER[node.diag_status]
+    group = M.HS_FOLDER[diag_status and diag_status.value]
   else
-    group = M.HS_FILE[node.diag_status]
+    group = M.HS_FILE[diag_status and diag_status.value]
   end
 
   if group then
@@ -35,7 +37,8 @@ end
 ---@return HighlightedString|nil modified icon
 function M.get_icon(node)
   if node and M.config.diagnostics.enable and M.config.renderer.icons.show.diagnostics then
-    return M.ICON[node.diag_status]
+    local diag_status = diagnostics.get_diag_status(node)
+    return M.ICON[diag_status and diag_status.value]
   end
 end