pdfLaTeX vs XeLaTeX vs LuaLaTeX, timed on 60,376 compiles
pdfLaTeX was the quickest: half of its compiles finished within 5.1 seconds. LuaLaTeX took 9.2 and XeLaTeX 14.3, and XeLaTeX documents failed most often. Measured on LetX, 29 June to 27 September 2026.
| Engine | Share of compiles | Compiles | Median (s) | 9 in 10 within (s) | Succeeded |
|---|---|---|---|---|---|
| pdfLaTeX | 85.8% | 51,805 | 5.1 | 20.6 | 92.3% |
| LuaLaTeX | 4.0% | 2,432 | 9.2 | 37.8 | 85.7% |
| XeLaTeX | 10.2% | 6,139 | 14.3 | 39.4 | 76.5% |
Time runs from the compile request reaching our server to the PDF being ready, queue included. Successful compiles only for the times.
How this was measured
- Every compile run on LetX in the window: 60,376 of them, by 2,946 people in 5,397 projects, all on the same servers with TeX Live.
- Only metadata was read: when each compile started and finished, whether it succeeded, and which engine its project uses. No document or log was opened.
- Nobody chose documents for the test. People pick their engine for their own reasons, so each engine's figures reflect the documents written in it, not the engine alone. XeLaTeX and LuaLaTeX carry more font-heavy and multilingual work.
What else the compiles show
- Midweek is busiest. Wednesday had the most compiles (9,687) and Saturday the fewest (6,787), about 43% more on the busiest day.
- Most projects are one file. The median project holds a single document; one in ten has 17 or more.
- A third cite with BibTeX or biblatex. 32.6% of projects compiled in the window include a .bib file.
- CVs lead. Of projects started from a template, 36% began from a CV or résumé.
Which engine to use
Start with pdfLaTeX. Switch to XeLaTeX or LuaLaTeX when you need a system font or a script pdfLaTeX cannot set, and if a compile stops over a font, add the font file to the project. More on the difference in how to compile LaTeX online, and the full picture of LetX in LetX by the numbers.
Frequently asked questions
Is XeLaTeX slower than pdfLaTeX?
In our data, yes: the median XeLaTeX compile took 14.3 seconds against 5.1 for pdfLaTeX, measured end to end on the same servers over 60,376 compiles. Part of that gap is the documents themselves, since people choose XeLaTeX for system fonts and non-Latin scripts, which cost time in any engine.
Is LuaLaTeX faster than XeLaTeX?
In our data, yes: a median of 9.2 seconds against 14.3 for XeLaTeX. Both were slower than pdfLaTeX, whose median was 5.1 seconds.
Which LaTeX engine should I use?
pdfLaTeX, unless you need a system font such as Times New Roman or a script it cannot typeset, such as Arabic, Bengali or Chinese. Then use XeLaTeX or LuaLaTeX with fontspec, and expect compiles to take longer.
Why do XeLaTeX documents fail more often?
Our logs do not say for most failures, but one cause they name again and again is a font. XeLaTeX and LuaLaTeX can only use fonts installed where the document compiles, and a document that asks for one by name (Aptos, Garamond, a font from someone's laptop) stops there. Put the font files in the project, or pick a font that ships with TeX Live.
Data questions or a larger cut: support@letx.app.