From b8c1691bd781d347787610a1b43d71b745c2dfc9 Mon Sep 17 00:00:00 2001
From: Pete Matsyburka <pete@docuseal.com>
Date: Wed, 9 Sep 2026 12:46:28 +0300
Subject: [PATCH] optimize xlsx export

---
 Gemfile                                  |  3 ++-
 Gemfile.lock                             |  9 +++++----
 config/initializers/autoload.rb          |  2 +-
 lib/submissions/generate_export_files.rb | 19 ++++++++-----------
 4 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/Gemfile b/Gemfile
index e2d74068..99e771b9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -36,7 +36,7 @@ gem 'rotp'
 gem 'rouge', require: false
 gem 'rqrcode', require: false
 gem 'ruby-vips'
-gem 'rubyXL', require: false
+gem 'rubyzip', require: false
 gem 'shakapacker'
 gem 'sidekiq'
 gem 'sqlite3', require: false
@@ -45,6 +45,7 @@ gem 'trilogy', require: false
 gem 'turbo-rails'
 gem 'twitter_cldr', require: false
 gem 'tzinfo-data'
+gem 'xlsxtream', require: false
 
 group :development, :test do
   gem 'better_html'
diff --git a/Gemfile.lock b/Gemfile.lock
index d320a892..5dc77e9f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -497,9 +497,6 @@ GEM
     ruby-vips (2.3.0)
       ffi (~> 1.12)
       logger
-    rubyXL (3.4.35)
-      nokogiri (>= 1.10.8)
-      rubyzip (>= 3.2.2)
     rubyzip (3.2.2)
     securerandom (0.4.1)
     semantic_range (3.1.1)
@@ -575,10 +572,13 @@ GEM
       base64
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
+    xlsxtream (3.1.0)
+      zip_kit (>= 6.2, < 7)
     xpath (3.2.0)
       nokogiri (~> 1.8)
     yaml (0.4.0)
     zeitwerk (2.8.2)
+    zip_kit (6.3.4)
 
 PLATFORMS
   aarch64-linux
@@ -638,7 +638,7 @@ DEPENDENCIES
   rubocop-rails
   rubocop-rspec
   ruby-vips
-  rubyXL
+  rubyzip
   shakapacker
   sidekiq
   simplecov
@@ -650,6 +650,7 @@ DEPENDENCIES
   tzinfo-data
   web-console
   webmock
+  xlsxtream
 
 RUBY VERSION
   ruby 4.0.5
diff --git a/config/initializers/autoload.rb b/config/initializers/autoload.rb
index 99dc4962..fd307b35 100644
--- a/config/initializers/autoload.rb
+++ b/config/initializers/autoload.rb
@@ -2,7 +2,7 @@
 
 autoload :CSV, 'csv'
 autoload :CSVSafe, 'csv-safe'
-autoload :RubyXL, 'rubyXL'
+autoload :Xlsxtream, 'xlsxtream'
 autoload :Zip, 'zip'
 autoload :Numo, 'numo/narray'
 autoload :OnnxRuntime, 'onnxruntime'
diff --git a/lib/submissions/generate_export_files.rb b/lib/submissions/generate_export_files.rb
index f1096db2..57e751b4 100644
--- a/lib/submissions/generate_export_files.rb
+++ b/lib/submissions/generate_export_files.rb
@@ -19,22 +19,19 @@ module Submissions
     end
 
     def rows_to_xlsx(rows)
-      workbook = RubyXL::Workbook.new
-      worksheet = workbook[0]
-      worksheet.sheet_name = Time.current.to_date.to_s
-
       headers = build_headers(rows)
-      headers.each_with_index do |column_name, column_index|
-        worksheet.add_cell(0, column_index, column_name)
-      end
 
-      rows.each.with_index(1) do |row, row_index|
-        extract_columns(row, headers).each_with_index do |value, column_index|
-          worksheet.add_cell(row_index, column_index, value)
+      io = StringIO.new
+
+      Xlsxtream::Workbook.open(io) do |workbook|
+        workbook.write_worksheet(Time.current.to_date.to_s) do |sheet|
+          sheet << headers.to_a
+
+          rows.each { |row| sheet << extract_columns(row, headers) }
         end
       end
 
-      workbook.stream.string
+      io.string
     end
 
     def rows_to_csv(rows)