diff --git a/dlibrary/dlibrary.py b/dlibrary/dlibrary.py
index df518ff..38b0cfb 100755
--- a/dlibrary/dlibrary.py
+++ b/dlibrary/dlibrary.py
@@ -14,6 +14,7 @@ import shutil
 import sqlite3
 import stat
 import textwrap
+import time
 import unicodedata
 from urllib.parse import urlparse
 import zipfile
@@ -105,7 +106,7 @@ READONLY_DIR = READONLY_FILE | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH
 debug_mode = False
 def debug(s):
     if debug_mode:
-        print(s)
+        print(f'{time.strftime("%Y-%m-%d %H:%M:%S")} - {s}')
 
 def open_zipfile_with_encoding(path):
     for enc in ["utf-8", "shift-jis", "shift-jisx0213"]:
@@ -1046,8 +1047,7 @@ def copy_recursive(src, dest):
 
 
 memoized_similarities = {}
-
-def similarity(a, b):
+def similarity(a, b, cache_cur=None):
     if len(a) < len(b) or (len(a) == len(b) and a < b):
         shorter = a
         longer = b
@@ -1060,13 +1060,22 @@ def similarity(a, b):
     if (shorter, longer) in memoized_similarities:
         return memoized_similarities[(shorter, longer)]
 
-    options = [similarity(shorter[1:], longer)]
-    for i in range(1, len(shorter)+1):
-        match_idx = longer.find(shorter[:i])
-        if match_idx == -1:
-            break
-        options.append(i*i + similarity(shorter[i:], longer[match_idx+i:]))
-    result = max(options)
+    if cache_cur and (cached := cache_cur.execute("SELECT similarity FROM similarities WHERE shorter = ? AND longer = ?", (shorter, longer)).fetchone()) is not None:
+        result = cached[0]
+    else:
+        options = [similarity(shorter[1:], longer)]
+        for i in range(1, len(shorter)+1):
+            match_idx = longer.find(shorter[:i])
+            if match_idx == -1:
+                break
+            options.append(i*i + similarity(shorter[i:], longer[match_idx+i:]))
+        result = max(options)
+
+        if cache_cur:
+            cache_cur.execute(
+                "INSERT INTO similarities(shorter, longer, similarity) VALUES(?, ?, ?)",
+                (shorter, longer, result),
+            )
 
     memoized_similarities[(shorter, longer)] = result
     return result
@@ -1090,6 +1099,7 @@ def top(items, n, key, overflow=0):
     return [item for (item, score) in winners[:n+overflow]]
 
 def generate(args):
+    debug('loading templates')
     jenv = Environment(
         loader=PackageLoader("dlibrary"),
         autoescape=select_autoescape()
@@ -1099,16 +1109,29 @@ def generate(args):
     categorization_template = jenv.get_template("categorization.html")
     work_template = jenv.get_template("work.html")
     index_template = jenv.get_template("index.html")
+    debug('templates loaded')
 
+    debug('opening main database')
     con = sqlite3.connect(args.destdir / 'meta.db')
     cur = con.cursor()
+    debug('main database open')
+
+    debug('opening cache database')
+    cache_con = sqlite3.connect(args.destdir / 'cache.db')
+    cache_cur = cache_con.cursor()
+    cache_cur.execute("CREATE TABLE IF NOT EXISTS similarities(shorter TEXT, longer TEXT, similarity INT, PRIMARY KEY(shorter, longer))")
+    debug('cache database open')
 
     site_dir = args.destdir / 'site'
 
     collated_work_ids = {p.name for p in (site_dir / 'images').iterdir()}
 
     works = []
-    for (work_id, title, circle, date, description, series) in cur.execute('SELECT id, title, circle, date, description, series FROM works ORDER BY date DESC').fetchall():
+    debug('checking thumbnail files')
+    thumbnail_files = {f.stem: f for f in (site_dir / 'thumbnails').iterdir()}
+    debug(f'{len(thumbnail_files)} thumbnail files found')
+    debug('running database query for works')
+    for (idx, (work_id, title, circle, date, description, series)) in enumerate(cur.execute('SELECT id, title, circle, date, description, series FROM works ORDER BY date DESC').fetchall()):
         if work_id not in collated_work_ids:
             continue
         authors = [author for (author,) in cur.execute('SELECT author FROM authors WHERE work = ?', (work_id,))]
@@ -1117,12 +1140,7 @@ def generate(args):
         images = [path.name for path in (site_dir / 'images' / work_id).iterdir()]
         images.sort()
 
-        try:
-            thumbnail_path = relpath(next(
-                f for f in (site_dir / 'thumbnails').iterdir() if f.stem == work_id
-            ), site_dir)
-        except StopIteration:
-            thumbnail_path = f'images/{work_id}/{images[0]}'
+        thumbnail_path = relpath(thumbnail_files.get(work_id, site_dir / 'images' / work_id / images[0]), site_dir)
         work = {
             'id': work_id,
             'title': title,
@@ -1137,13 +1155,16 @@ def generate(args):
         }
         works.append(work)
 
+        print(f'\x1b[2K\r{idx+1} database entries read...', end='')
+    print()
+
     for (idx, work) in enumerate(works):
         def suggestion_priority(other_work):
             if other_work is work:
                 return -2
             if work['series'] and work['series'] == other_work['series']:
                 return -1
-            return similarity(work['title'], other_work['title'])
+            return similarity(work['title'], other_work['title'], cache_cur)
         suggested = top(works, SUGGESTED_WORKS_COUNT, suggestion_priority)
 
         work_dir = site_dir / 'works' / work['id']
@@ -1155,6 +1176,7 @@ def generate(args):
             f.write(viewer_template.render(depth=3, work=work, title=work['title']))
 
         print(f'\x1b[2K\r{idx+1}/{len(works)} works processed...', end=('' if idx+1 < len(works) else '\n'))
+    cache_con.commit()
 
     uca = pyuca.Collator().sort_key
     def make_categorization(categorization, query, work_filter, work_style_cards=False):
@@ -1162,7 +1184,7 @@ def generate(args):
 
         cats = sorted((cat for (cat,) in cur.execute(query)), key=uca)
         cat_samples = {}
-        for cat in cats:
+        for (idx, cat) in enumerate(cats):
             cat_works = list(filter(work_filter(cat), works))
             cat_samples[cat] = cat_works[0] if len(cat_works) > 0 else None
 
@@ -1176,6 +1198,7 @@ def generate(args):
                     title=cat,
                     categorization=categorization,
                 ))
+            print(f'\x1b[2K\r{idx+1}/{len(cats)} {categorization} processed...', end=('' if idx+1 < len(cats) else '\n'))
 
         categorization_dir.mkdir(parents=True, exist_ok=True)
         with open(categorization_dir / 'index.html', 'w') as f:
@@ -1209,13 +1232,23 @@ def generate(args):
         work_style_cards=True,
     )
 
+    debug('copying static files')
     with resources.as_file(resources.files("dlibrary")) as r:
         copy_recursive(r / 'static', site_dir / 'static')
+    debug('static files copied')
 
+    debug('writing index page')
     with open(site_dir / 'index.html', 'w') as f:
         f.write(index_template.render(depth=0, works=works))
+    debug('index page written')
 
+    debug('closing cache database')
+    cache_con.close()
+    debug('cache database closed')
+
+    debug('closing main database')
     con.close()
+    debug('main database closed')
 
 
 argparser = argparse.ArgumentParser(