(core) Python optimizations to speed up data engine

Summary:
- A bunch of optimizations guided by python profiling (esp. py-spy)
- Big one is optimizing Record/RecordSet attribute access
- Adds tracemalloc printout when running test_replay with PYTHONTRACEMALLOC=1 (on PY3)
  (but memory size is barely affected by these changes)

- Testing with RECORD_SANDBOX_BUFFERS_DIR, loading and calculating a particular
  very large doc (CRM), time taken improved from 73.9s to 54.8s (26% faster)

Test Plan: No behavior changes intended; relying on existing tests to verify that.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3781

sandbox/grist/lookup.py

@@ -161,9 +161,9 @@ class SimpleLookupMapColumn(BaseLookupMapColumn):
   def _recalc_rec_method(self, rec, table):
     old_key = self._row_key_map.lookup_left(rec._row_id)
 
-    # Note that rec._get_col(_col_id) is what creates the correct dependency, as well as ensures
+    # Note that getattr(rec, _col_id) is what creates the correct dependency, as well as ensures
     # that the columns used to index by are brought up-to-date (in case they are formula columns).
-    new_key = tuple(_extract(rec._get_col(_col_id)) for _col_id in self._col_ids_tuple)
+    new_key = tuple(_extract(getattr(rec, _col_id)) for _col_id in self._col_ids_tuple)
 
     try:
       self._row_key_map.insert(rec._row_id, new_key)
@@ -188,9 +188,9 @@ class ContainsLookupMapColumn(BaseLookupMapColumn):
     # looked up with CONTAINS()
     new_keys_groups = []
     for col_id in self._col_ids_tuple:
-      # Note that _get_col is what creates the correct dependency, as well as ensures
+      # Note that getattr() is what creates the correct dependency, as well as ensures
       # that the columns used to index by are brought up-to-date (in case they are formula columns).
-      group = rec._get_col(extract_column_id(col_id))
+      group = getattr(rec, extract_column_id(col_id))
 
       if isinstance(col_id, _Contains):
         # Check that the cell targeted by CONTAINS() has an appropriate type.