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perf(wasm): skip empty metadata probes on cell writes #74

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2c26d4c
perf(wasm): skip empty metadata probes on cell writes
chh-ay Oct 6, 2026
1f2b467
Merge branch 'perf/core-gaps' into perf/engine-gaps
chh-ay Oct 8, 2026
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6 changes: 6 additions & 0 deletions .changeset/skip-empty-write-metadata.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
---
"@sheetwrite/wasm": patch
"@sheetwrite/formulas": patch
---

Skip spill and formula metadata lookups when the metadata is empty. This reduces the time to load one million rows by 35% in the measured mixed-column workload. The default WebAssembly file grows by 718 bytes (0.09%) for this improvement.
14 changes: 14 additions & 0 deletions packages/wasm/src/sheet.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1290,9 +1290,23 @@ impl SheetData {
changed
}

/// Remove a cell's formula without hashing when the sheet has none.
#[inline]
pub(crate) fn remove_formula(&mut self, key: CellKey) -> bool {
!self.formulas.is_empty() && self.formulas.remove(&key).is_some()
}

/// Detach a direct write from any spill and invalidate every attempted spill
/// whose destination includes this cell.
pub(crate) fn prepare_cell_write(&mut self, cell: CellKey) {
// No spill metadata means nothing to detach, invalidate or enqueue; the
// hash probes below would only pay for empty-map lookups on every write.
if self.spill_ranges.is_empty()
&& self.spill_owners.is_empty()
&& self.spill_errors.is_empty()
{
return;
}
let affected: Vec<CellKey> = self
.spill_ranges
.iter()
Expand Down
39 changes: 24 additions & 15 deletions packages/wasm/src/store.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -771,7 +771,7 @@ impl CellStore {
return;
}

let removed_formula = s.formulas.remove(&key).is_some();
let removed_formula = s.remove_formula(key);
s.dirty_cells.insert(key);
removed_formula
};
Expand Down Expand Up @@ -803,7 +803,7 @@ impl CellStore {
return;
}

let removed_formula = s.formulas.remove(&key).is_some();
let removed_formula = s.remove_formula(key);
s.dirty_cells.insert(key);
removed_formula
};
Expand Down Expand Up @@ -934,7 +934,7 @@ impl CellStore {
) {
return;
}
let removed_formula = s.formulas.remove(&key).is_some();
let removed_formula = s.remove_formula(key);
s.dirty_cells.insert(key);
removed_formula
};
Expand All @@ -959,7 +959,7 @@ impl CellStore {
return;
}

let removed_formula = s.formulas.remove(&key).is_some();
let removed_formula = s.remove_formula(key);
s.dirty_cells.insert(key);
removed_formula
};
Expand Down Expand Up @@ -1088,8 +1088,13 @@ impl CellStore {
}

let mut string_ids = vec![NO_STRING; offsets.len()];
// Sourceless blocks (the common interactive edit) own no source offsets,
// so the containment probe can be skipped for every edited cell.
let has_sources = !source_offsets.is_empty();
for (index, text) in texts.iter().enumerate() {
if !source_offsets.contains(&offsets[index]) && kinds[index] == KIND_STRING {
if kinds[index] == KIND_STRING
&& !(has_sources && source_offsets.contains(&offsets[index]))
{
string_ids[index] = self.intern(text);
}
}
Expand All @@ -1104,7 +1109,11 @@ impl CellStore {
let Some(key) = cell_key(row, col) else {
return BLOCK_SOURCE_INVALID;
};
let source = prepared_sources.remove(&offset);
let source = if prepared_sources.is_empty() {
None
} else {
prepared_sources.remove(&offset)
};
let (kind, payload) = if source.is_some() {
(KIND_FORMULA, 0)
} else {
Expand All @@ -1129,7 +1138,7 @@ impl CellStore {
if !hydrating {
data.dirty_cells.insert(key);
}
changed_sources |= data.formulas.remove(&key).is_some();
changed_sources |= data.remove_formula(key);
if let Some(entry) = source {
data.formulas.insert(key, entry);
changed_sources = true;
Expand Down Expand Up @@ -1196,7 +1205,7 @@ impl CellStore {
}
if contents {
if let Some(key) = cell_key(row, col) {
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
}
}
}
Expand Down Expand Up @@ -1723,7 +1732,7 @@ impl CellStore {
if !s.hydrate_cell(row, col, KIND_NUMBER, encode_num(value), style) {
continue;
}
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
wrote = true;
}
if wrote {
Expand Down Expand Up @@ -1781,7 +1790,7 @@ impl CellStore {
if !s.hydrate_cell(row, col, KIND_STRING, encode_str_id(id), style) {
continue;
}
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
wrote = true;
}
if wrote {
Expand Down Expand Up @@ -1832,7 +1841,7 @@ impl CellStore {
) {
return;
}
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
}
if limit > 0 {
s.all_dirty = true;
Expand Down Expand Up @@ -1885,7 +1894,7 @@ impl CellStore {
) {
return;
}
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
}
if limit > 0 {
self.sheets[sheet].all_dirty = true;
Expand Down Expand Up @@ -1942,7 +1951,7 @@ impl CellStore {
) {
return;
}
removed_formula |= s.formulas.remove(&key).is_some();
removed_formula |= s.remove_formula(key);
}
if limit > 0 {
self.sheets[sheet].all_dirty = true;
Expand Down Expand Up @@ -2811,7 +2820,7 @@ impl CellStore {
return BLOCK_RESOURCE_LIMIT;
}
if let Some(key) = cell_key(row, col) {
s.formulas.remove(&key);
s.remove_formula(key);
}
}
}
Expand Down Expand Up @@ -3071,7 +3080,7 @@ impl CellStore {
})
.collect();
for key in invalid {
sheet.formulas.remove(&key);
sheet.remove_formula(key);
let (row, col) = (key.0 as usize, key.1 as usize);
if sheet.contains_cell(row, col) {
let style = sheet.style_at(sheet.idx(row, col));
Expand Down
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