diff --git a/src/calltree.js b/src/calltree.js
index 9242c1a..a190140 100644
--- a/src/calltree.js
+++ b/src/calltree.js
@@ -468,76 +468,6 @@ const click = (state, id) => {
   }
 }
 
-/*
-After find_call, we have two calltrees that have common subtree (starting from
-root node). Nodes in these subtrees are the same, but have different ids. Copy
-nodes that are in the second tree that are not in the first tree
-*/
-const merge_calltrees = (a, b) => do_merge_calltrees(a, b)[1]
-
-const do_merge_calltrees = (a, b) => {
-  // TODO Quick workaround, should be fixed by not saving stack in eval.js in
-  // case of stackoverflow
-  if(!a.ok && is_stackoverflow(a)) {
-    return [false, a]
-  }
-
-  if(a.has_more_children) {
-    if(b.has_more_children) {
-      return [false, a]
-    } else {
-      // Preserve id
-      return [true, {...b, id: a.id}]
-    }
-  }
-
-  if(a.children == null) {
-    return [false, a]
-  }
-  
-  if(b.has_more_children) {
-    return [false, a]
-  }
-
-  const [has_update, children] = map_accum(
-    (has_update, c, i) => {
-      const [upd, merged] = do_merge_calltrees(c, b.children[i])
-      return [has_update || upd, merged]
-    },
-    false,
-    a.children
-  )
-
-  if(has_update) {
-    return [true, {...a, children}]
-  } else {
-    return [false, a]
-  }
-}
-
-/*
-  Finds node in calltree `a` that has the same position that node with id `id`
-  in calltree `b`. Null if not found
-*/
-const find_same_node = (a, b, id) => {
-  if(b == null) {
-    return null
-  }
-
-  if(b.id == id) {
-    return a
-  }
-
-  if(a.children == null || b.children == null) {
-    return null
-  }
-
-  return map_find(
-    a.children,
-    (c, i) => find_same_node(c, b.children[i], id)
-  )
-}
-
 export const expand_path = (state, node) => ({
   ...state,
   calltree_node_is_expanded: {
@@ -651,55 +581,48 @@ export const find_call = (state, index) => {
   }
 
   const loc = {index: node.index, module: state.current_module}
-  const {
-    calltree, 
-    call, 
-    is_found_deferred_call, 
-    deferred_call_index
-  } = state.calltree_actions.find_call(
-    loc, 
-    get_deferred_calls(state)
+  
+  // First try to find node among existing calltree nodes
+  const call = find_node(state.calltree, node => 
+    true
+    && node.fn != null
+    && node.fn.__location != null
+    && node.fn.__location.index == loc.index
+    && node.fn.__location.module == loc.module
   )
-  if(call == null) {
-    return add_calltree_node_by_loc(
-      // Remove active_calltree_node
-      // current_calltree_node may stay not null, because it is calltree node
-      // explicitly selected by user in calltree view
-      set_active_calltree_node(state, null),
-      loc,
-      null
-    )
-  }
 
   let next_calltree, active_calltree_node
 
-  if(is_found_deferred_call) {
-    const deferred_calls = get_deferred_calls(state)
-    const prev_call = deferred_calls[deferred_call_index]
-    const merged = merge_calltrees(prev_call, calltree)
-    const next_deferred_calls = deferred_calls.map((c, i) => 
-      i == deferred_call_index
-        ? merged
-        : c
-    )
-    next_calltree = make_calltree(
-      root_calltree_node(state),
-      next_deferred_calls,
-    )
-    active_calltree_node = find_same_node(
-      merged,
-      calltree,
-      call.id
-    )
+  if(call != null) {
+    if(call.has_more_children) {
+      active_calltree_node = state.calltree_actions.expand_calltree_node(call)
+      next_calltree = replace_calltree_node(
+        state.calltree, 
+        call, 
+        active_calltree_node
+      )
+    } else {
+      active_calltree_node = call
+      next_calltree = state.calltree
+    }
   } else {
-    next_calltree = make_calltree(
-      merge_calltrees(root_calltree_node(state), calltree),
-      get_deferred_calls(state),
-    )
-    active_calltree_node = find_same_node(
-      root_calltree_node({calltree: next_calltree}),
-      calltree, 
-      call.id
+    const find_result = state.calltree_actions.find_call(state.calltree, loc)
+    if(find_result == null) {
+      return add_calltree_node_by_loc(
+        // Remove active_calltree_node
+        // current_calltree_node may stay not null, because it is calltree node
+        // explicitly selected by user in calltree view
+        set_active_calltree_node(state, null),
+        loc,
+        null
+      )
+    }
+
+    active_calltree_node = find_result.call
+    next_calltree = replace_calltree_node(
+      state.calltree, 
+      find_node(state.calltree, n => n.id == find_result.node.id),
+      find_result.node,
     )
   }
 
diff --git a/src/eval.js b/src/eval.js
index b741f3d..e1a962b 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -7,6 +7,7 @@ import {
 
 import {
   find_fn_by_location, 
+  find_node,
   collect_destructuring_identifiers,
   map_destructuring_identifiers,
   map_tree,
@@ -334,19 +335,7 @@ export const eval_modules = (
       }
     }
 
-    const expand_calltree_node = (node) => {
-      is_recording_deferred_calls = false
-      children = null
-      try {
-        if(node.is_new) {
-          new node.fn(...node.args)
-        } else {
-          node.fn.apply(node.context, node.args)
-        }
-      } catch(e) {
-        // do nothing. Exception was caught and recorded inside 'trace'
-      }
-      is_recording_deferred_calls = true
+    const do_expand_calltree_node = node => {
       if(node.fn.__location != null) {
         // fn is hosted, it created call, this time with children
         const result = children[0]
@@ -363,6 +352,22 @@ export const eval_modules = (
       }
     }
 
+    const expand_calltree_node = (node) => {
+      is_recording_deferred_calls = false
+      children = null
+      try {
+        if(node.is_new) {
+          new node.fn(...node.args)
+        } else {
+          node.fn.apply(node.context, node.args)
+        }
+      } catch(e) {
+        // do nothing. Exception was caught and recorded inside 'trace'
+      }
+      is_recording_deferred_calls = true
+      return do_expand_calltree_node(node)
+    }
+
     const run_and_find_call = (location) => {
       searched_location = location
 
@@ -390,47 +395,76 @@ export const eval_modules = (
       }
     }
 
-    const find_call = (location, deferred_calls) => {
-      searched_location = location
-      let is_found_deferred_call = false
-      let i
 
-      let {calltree, modules, logs} = run()
+    /*
+      Try to find call of function with given 'location'
 
-      is_recording_deferred_calls = false
-      if(found_call == null && deferred_calls != null) {
-        for(i = 0; i < deferred_calls.length; i++) {
-          const c = deferred_calls[i]
+      Function is synchronous, because we recorded calltree nodes for all async
+      function calls. Here we walk over calltree, find leaves that have
+      'has_more_children' set to true, and rerunning fns in these leaves with
+      'searched_location' being set, until we find find call or no children
+      left.
+
+      We dont rerun entire execution because we want find_call to be
+      synchronous for simplicity
+    */
+    const find_call = (calltree, location) => {
+      // TODO remove
+      if(children != null) {
+        throw new Error('illegal state')
+      }
+
+      const do_find = node => {
+        if(node.children != null) {
+          for(let c of node.children) {
+            const result = do_find(c)
+            if(result != null) {
+              return result
+            }
+          }
+          // call was not find in children, return null
+          return null
+        }
+
+
+        if(node.has_more_children) {
           try {
-            c.fn.apply(c.context, c.args)
+            if(node.is_new) {
+              new node.fn(...node.args)
+            } else {
+              node.fn.apply(node.context, node.args)
+            }
           } catch(e) {
             // do nothing. Exception was caught and recorded inside 'trace'
           }
+
           if(found_call != null) {
-            is_found_deferred_call = true
-            calltree = children[0]
+            return {
+              node: do_expand_calltree_node(node),
+              call: found_call,
+            }
+          } else {
             children = null
-            break
           }
         }
+
+        // node has no children, return null
+        return null
       }
 
+      is_recording_deferred_calls = false
+      searched_location = location
+
+      const result = do_find(calltree)
+
+      children = null
+      searched_location = null
+      found_call = null
       is_recording_deferred_calls = true
 
-      searched_location = null
-      const call = found_call
-      found_call = null
-      return {
-        is_found_deferred_call, 
-        deferred_call_index: i, 
-        calltree, 
-        call,
-        modules,
-        logs,
-      }
+      return result
     }
 
-
     const __do_await = async value => {
       // children is an array of child calls for current function call. But it
       // can be null to save one empty array allocation in case it has no child
@@ -733,24 +767,17 @@ export const eval_modules = (
       const expanded = actions.expand_calltree_node(node)
       return assign_code(parse_result.modules, expanded)
     },
-    find_call: (loc, deferred_calls) => {
-      const {
-        is_found_deferred_call, 
-        deferred_call_index, 
-        calltree, 
-        call,
-        modules,
-        logs,
-      } = actions.find_call(loc, deferred_calls)
+    find_call: (calltree, location) => {
+      const result = actions.find_call(calltree, location)
+      if(result == null) {
+        return null
+      }
+      const {node, call} = result
+      const node_with_code = assign_code(parse_result.modules, node)
+      const call_with_code = find_node(node_with_code, n => n.id == call.id)
       return {
-        is_found_deferred_call,
-        deferred_call_index,
-        calltree: assign_code(parse_result.modules, calltree),
-        // TODO: `call` does not have `code` property here. Currently it is
-        // worked around by callers. Refactor
-        call,
-        modules,
-        logs,
+        node: node_with_code,
+        call: call_with_code,
       }
     }
   }
diff --git a/test/test.js b/test/test.js
index 0ae49d2..5b5173f 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1397,6 +1397,7 @@ export const tests = [
 
   test('coloring nested', () => {
     const code = 
+    // TODO reformat using .trim()
     `const x = () => {
    return () => {
      return 123
@@ -1801,7 +1802,7 @@ const y = x()`
     assert_equal(s.current_calltree_node.toplevel, true)
   }),
 
-  //TODO this test is fine standalone, but it breaks self-hosted
+  //TODO this test is fine standalone, but it breaks self-hosted test
   /*
   test('unwind_stack overflow', () => {
     const s = test_initial_state(`