diff --git a/img/fzn_circ.jpg b/img/fzn_circ.jpg
new file mode 100644
index 0000000..8440340
Binary files /dev/null and b/img/fzn_circ.jpg differ
diff --git a/img/stephen_circ.jpg b/img/stephen_circ.jpg
new file mode 100644
index 0000000..79e05c5
Binary files /dev/null and b/img/stephen_circ.jpg differ
diff --git a/slides.tex b/slides.tex
index 254ab8b..2de12a2 100644
--- a/slides.tex
+++ b/slides.tex
@@ -33,12 +33,6 @@
 \setbeamertemplate{navigation symbols}{}
 \setbeamertemplate{headline}{}
 
-\newcommand{\thenalert}[1]{\only<1>{#1}\only<2>{\alert{#1}}}
-\newcommand{\slidecountline}{
-    \ifthenelse{\theframenumber = 0}
-        {}
-        {\insertframenumber/\inserttotalframenumber}}
-
 \newcommand{\cmark}{\color{OliveGreen}\ding{52}}
 \newcommand{\xmark}{\color{BrickRed}\ding{56}}
 
@@ -46,6 +40,8 @@
 \let\temptwo\enditemize
 \renewenvironment{itemize}{\tempone\addtolength{\itemsep}{0.5\baselineskip}}{\temptwo}
 
+
+
 \newcommand{\sectiontitleframe}{
     \begin{frame}
         \vfill
@@ -65,6 +61,12 @@
     sensitive=false,
 }
 
+\newcommand{\thenalert}[1]{\only<1>{#1}\only<2>{\alert{#1}}}
+\newcommand{\slidecountline}{
+    \ifthenelse{\theframenumber = 0}
+        {}
+        {\insertframenumber/\inserttotalframenumber}}
+
 \setbeamertemplate{footline}
 {
   \leavevmode%
@@ -79,6 +81,23 @@
   \vskip0pt%
 }
 
+\setbeamercolor{block title}{use=structure,fg=white,bg=structure.fg!75!black}
+\setbeamercolor{block title alerted}{use=alerted text,fg=white,bg=alerted
+text.fg!75!black}
+\setbeamercolor{block title example}{use=example text,fg=white,bg=example
+text.fg!75!black}
+
+%\setbeamertemplate{frametitle}{
+%  \leavevmode%
+%  \hbox{%
+%  \begin{beamercolorbox}[wd=\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
+%    \usebeamerfont{author in head/foot}\insertframetitle
+%  \end{beamercolorbox}%
+%  }
+%  \vskip0pt%
+%    %\color{black}\bfseries\insertframetitle\par\vskip-6pt\hrulefill
+%}
+
 
 \newcolumntype{b}{X}
 \newcolumntype{s}{>{\hsize=.43\hsize}X}
@@ -104,6 +123,7 @@
 
     \vspace{-2em}
 
+
     \begin{columns}
         \begin{column}{0.55\textwidth}
             \begin{tcolorbox}[halign=center, colframe=blue]
@@ -111,7 +131,7 @@
 
                 \smallskip
                 \vspace{0.5em}
-                {\url{https://huit.re/frdwarf}}\\
+                {\small\url{https://huit.re/frdwarf}}\\
                 \vspace{0.5em}
             \end{tcolorbox}
         \end{column}
@@ -127,6 +147,13 @@
             \end{tcolorbox}
         \end{column}
     \end{columns}
+
+    \begin{textblock*}{0.22\textwidth}[0.5,0](0.15\paperwidth,0.38\paperheight)%
+        \includegraphics[width=\linewidth]{img/stephen_circ.jpg}
+    \end{textblock*}
+    \begin{textblock*}{0.22\textwidth}[0.5,0](0.85\paperwidth,0.38\paperheight)%
+        \includegraphics[width=\linewidth]{img/fzn_circ.jpg}
+    \end{textblock*}
 \end{frame}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -569,16 +596,24 @@ Segmentation fault.
 \subsection{Results}
 
 \begin{frame}{Performances}
-    \begin{itemize}
-        \item \alert{Speedup}: x15 (\prog{gzip}) to x25 (\prog{hackbench}) vs.
-            libunwind
+    \begin{center}
+        \Large\bf Speedup vs. libunwind:
+        \begin{columns}
+            \begin{column}{0.5\textwidth}
+                \alert{x15} on gzip
+            \end{column}
+            \begin{column}{0.5\textwidth}
+                \alert{x25} on hackbench
+            \end{column}
+        \end{columns}
+    \end{center}
 
-            \begin{itemize}
-                \item libunwind: state of the art, aggressive caching.
-            \end{itemize}
+    \vfill
 
-        \item \alert{Space overhead}: x2.6 to x3 vs. DWARF
-    \end{itemize}
+    \begin{center}
+        \Large\bf Space overhead vs. DWARF:\\
+        \alert{x2.6 -- x3}
+    \end{center}
 \end{frame}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/src/lowlevellock_backtrace b/src/lowlevellock_backtrace
new file mode 100644
index 0000000..b90f90d
--- /dev/null
+++ b/src/lowlevellock_backtrace
@@ -0,0 +1,5 @@
+(gdb) backtrace
+#0 0x406c2c in _L_lock_19
+#1 0x406c2c in _L_lock_19
+#2 0x4069c6 in abort
+#3 0x401017 in main
diff --git a/src/main_cfi.s b/src/main_cfi.s
new file mode 100644
index 0000000..53838b7
--- /dev/null
+++ b/src/main_cfi.s
@@ -0,0 +1,8 @@
+main:
+.cfi_startproc
+pushq	%rbp
+.cfi_def_cfa_offset 16
+.cfi_offset 6, -16
+movq	%rsp, %rbp
+.cfi_def_cfa_register 6
+subq	$32, %rsp