utcfromtimestamp was deprecated and nobody told me,

not even the deprecationwarning that got silently generated burning
20~30% of all CPU-time without actually displaying it anywhere, nice

python 3.12.0 is now only 5% slower than 3.11.6

also fixes some other, less-performance-fatal deprecations

.vscode/tasks.json

@@ -11,6 +11,7 @@
             "type": "shell",
             "command": "${config:python.pythonPath}",
             "args": [
+                "-Wa", //-We
                 ".vscode/launch.py"
             ]
         }