diff --git a/crates/pdf/src/lib.rs b/crates/pdf/src/lib.rs
index 37909a1f5..f1e598967 100644
--- a/crates/pdf/src/lib.rs
+++ b/crates/pdf/src/lib.rs
@@ -215,6 +215,8 @@ pub fn parse_page_range(s: &str, count: usize) -> Result<Vec<usize>> {
     let bad = || PdfError::BadRange(s.to_string());
     let num = |v: &str| v.trim().parse::<usize>().map_err(|_| bad());
     let mut out = Vec::new();
+    // The pages selected so far, for ranges that overlap (`1-9, 2-8, …`): a set, not a search.
+    let mut selected = vec![false; count];
     for part in t.split(',').map(str::trim).filter(|p| !p.is_empty()) {
         let (a, b) = match part.split_once('-') {
             Some((a, b)) => {
@@ -234,7 +236,8 @@ pub fn parse_page_range(s: &str, count: usize) -> Result<Vec<usize>> {
             if p > count {
                 return Err(PdfError::BadPage(p));
             }
-            if !out.contains(&(p - 1)) {
+            if let Some(new) = selected.get_mut(p - 1).filter(|s| !**s) {
+                *new = true;
                 out.push(p - 1);
             }
         }
diff --git a/crates/pdf/src/optional_content.rs b/crates/pdf/src/optional_content.rs
index 374c0d1f1..08dbbe0bd 100644
--- a/crates/pdf/src/optional_content.rs
+++ b/crates/pdf/src/optional_content.rs
@@ -1,6 +1,7 @@
 use hayro_syntax::Pdf;
 use hayro_syntax::object::{Array, Dict, MaybeRef, Name, Object, ObjectIdentifier, Stream};
 use hayro_syntax::reader::{Reader, ReaderExt};
+use std::collections::HashSet;
 use std::sync::Arc;
 
 use crate::{PdfError, Result};
@@ -218,10 +219,12 @@ pub(crate) fn prepare(bytes: &Arc<Vec<u8>>, choice: Option<&[String]>) -> Result
         }
         Err(error) => return Err(error),
     };
-    if on.iter().any(|id| off.contains(id)) {
+    let off_set: HashSet<_> = off.iter().copied().collect();
+    if on.iter().any(|id| off_set.contains(id)) {
         return Err(invalid());
     }
-    let incomplete = on.iter().chain(&off).any(|id| !groups.contains(id));
+    let group_set: HashSet<_> = groups.iter().copied().collect();
+    let incomplete = on.iter().chain(&off).any(|id| !group_set.contains(id));
     groups.extend(on.iter().chain(&off).copied());
     groups.sort();
     groups.dedup();
diff --git a/crates/pdf/src/pdfx.rs b/crates/pdf/src/pdfx.rs
index 6d7a3714f..731a5989d 100644
--- a/crates/pdf/src/pdfx.rs
+++ b/crates/pdf/src/pdfx.rs
@@ -3,7 +3,7 @@
 //! krilla's PDF 1.6 output, and a check of the PDF/X-4 requirements this exporter is responsible
 //! for.
 
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 
 use hayro_syntax::content::UntypedIter;
 use hayro_syntax::object::{Array, Dict, Name, Object, ObjectIdentifier, Stream};
@@ -217,6 +217,7 @@ fn device_rgb(file: Option<&hayro_syntax::Pdf>) -> Vec<String> {
         return Vec::new();
     }
     let mut found: Vec<(String, Vec<usize>)> = Vec::new();
+    let mut at: HashMap<String, usize> = HashMap::new();
     for (i, page) in file.pages().iter().enumerate() {
         let mut scan = RgbScan::default();
         let res = page.resources();
@@ -227,9 +228,12 @@ fn device_rgb(file: Option<&hayro_syntax::Pdf>) -> Vec<String> {
             scan.content(content, res, 0);
         }
         for what in scan.found {
-            match found.iter_mut().find(|(w, _)| *w == what) {
+            match at.get(&what).and_then(|k| found.get_mut(*k)) {
                 Some((_, pages)) => pages.push(i + 1),
-                None => found.push((what, vec![i + 1])),
+                None => {
+                    at.insert(what.clone(), found.len());
+                    found.push((what, vec![i + 1]));
+                }
             }
         }
     }
@@ -274,14 +278,16 @@ pub(crate) const MAX_DEPTH: usize = 16;
 /// What one page uses in device RGB, in the order found.
 #[derive(Default)]
 struct RgbScan {
+    /// What was found, in the order found; `known` is the same as a set.
     found: Vec<String>,
+    known: HashSet<String>,
     /// Forms, images and patterns already looked at on this page.
     seen: HashSet<ObjectIdentifier>,
 }
 
 impl RgbScan {
     fn add(&mut self, what: String) {
-        if !self.found.contains(&what) {
+        if self.known.insert(what.clone()) {
             self.found.push(what);
         }
     }
diff --git a/crates/pdf/src/pdfx1a.rs b/crates/pdf/src/pdfx1a.rs
index 495a389d8..aa8873083 100644
--- a/crates/pdf/src/pdfx1a.rs
+++ b/crates/pdf/src/pdfx1a.rs
@@ -520,7 +520,9 @@ fn disallowed(cs: &Object<'_>, res: &Resources<'_>, depth: usize) -> Option<Stri
 /// What one page has that PDF/X-1a doesn't allow, in the order found.
 #[derive(Default)]
 struct Scan {
+    /// What was found, in the order found; `known` is the same as a set.
     found: Vec<String>,
+    known: HashSet<String>,
     font_issues: Vec<String>,
     seen: HashSet<ObjectIdentifier>,
     fonts: HashSet<ObjectIdentifier>,
@@ -528,7 +530,7 @@ struct Scan {
 
 impl Scan {
     fn add(&mut self, what: String) {
-        if !self.found.contains(&what) {
+        if self.known.insert(what.clone()) {
             self.found.push(what);
         }
     }
diff --git a/crates/pdf/src/tests.rs b/crates/pdf/src/tests.rs
index 262e19c8e..e582b4cde 100644
--- a/crates/pdf/src/tests.rs
+++ b/crates/pdf/src/tests.rs
@@ -178,6 +178,12 @@ fn spreads_and_ranges() {
     assert_eq!(parse_page_range("1-2, 4", 4).unwrap(), vec![0, 1, 3]);
     assert_eq!(parse_page_range("3-", 4).unwrap(), vec![2, 3]);
     assert_eq!(parse_page_range("", 2).unwrap(), vec![0, 1]);
+    // Ranges that overlap many times over: each page is selected once, in the order first named.
+    let overlapping = std::iter::repeat_n("1-20000, 5-19000", 500).collect::<Vec<_>>().join(",");
+    let t = std::time::Instant::now();
+    assert_eq!(parse_page_range(&overlapping, 20000).unwrap().len(), 20000);
+    assert!(t.elapsed() < std::time::Duration::from_secs(5), "{:?}", t.elapsed());
+    assert_eq!(parse_page_range("3, 1-3", 4).unwrap(), vec![2, 0, 1]);
     assert!(parse_page_range("5", 4).is_err());
     assert!(parse_page_range("x", 4).is_err());
     let bytes = export_pdf(&d, &Cache::new(), &PdfOptions { pages: Some(vec![1, 2]), ..Default::default() }).unwrap();