diff --git a/main/src/main/scala/sbt/internal/BuildDef.scala b/main/src/main/scala/sbt/internal/BuildDef.scala
index 181205a23..6ac7b226e 100644
--- a/main/src/main/scala/sbt/internal/BuildDef.scala
+++ b/main/src/main/scala/sbt/internal/BuildDef.scala
@@ -9,7 +9,10 @@
 package sbt
 package internal
 
+import com.github.benmanes.caffeine.cache.{ Cache as CCache, Caffeine, Weigher }
 import java.io.File
+import java.nio.file.{ Files, NoSuchFileException }
+import java.nio.file.attribute.BasicFileAttributes
 import Keys.{ organization, thisProject, autoGeneratedProject, publish, publishLocal, skip }
 import Def.Setting
 // import sbt.ProjectExtra.apply
@@ -18,7 +21,7 @@ import sbt.internal.util.{ Attributed, StringAttributeMap }
 import sbt.internal.inc.{ FileAnalysisStore, ReflectUtilities }
 import sbt.util.CacheImplicits.given
 import xsbti.{ FileConverter, VirtualFileRef }
-import xsbti.compile.CompileAnalysis
+import xsbti.compile.{ AnalysisContents, CompileAnalysis }
 
 trait BuildDef {
   def projectDefinitions(@deprecated("unused", "") baseDirectory: File): Seq[Project] = projects
@@ -87,6 +90,26 @@ private[sbt] object BuildDef:
   ): Seq[xsbti.compile.CompileAnalysis] =
     in.flatMap(a => extractAnalysis(a.metadata, converter))
 
+  private[sbt] final val localAnalysisCacheByteSize = 100 * 1024L * 1024L
+  private val weigher: Weigher[String, (Option[AnalysisContents], Long, Long)] = {
+    case (_, (_, _, sizeBytes)) => sizeBytes.toInt
+  }
+  private val inMemoryAnalysisCache: CCache[String, (Option[AnalysisContents], Long, Long)] =
+    Caffeine
+      .newBuilder()
+      .maximumWeight(localAnalysisCacheByteSize)
+      .weigher(weigher)
+      .build()
+  private def getOrElseUpdate(ref: VirtualFileRef, lastModified: Long, sizeBytes: Long)(
+      value: => Option[AnalysisContents]
+  ): Option[AnalysisContents] =
+    Option(inMemoryAnalysisCache.getIfPresent(ref.id())) match
+      case Some((v, mod, i)) if lastModified == mod && sizeBytes == i => v
+      case _ =>
+        val v = value
+        inMemoryAnalysisCache.put(ref.id(), (v, lastModified, sizeBytes))
+        v
+
   private[sbt] def extractAnalysis(
       metadata: StringAttributeMap,
       converter: FileConverter
@@ -94,10 +117,21 @@ private[sbt] object BuildDef:
     import sbt.OptionSyntax.*
     def asBinary(file: File) = FileAnalysisStore.binary(file).get.asScala
     def asText(file: File) = FileAnalysisStore.text(file).get.asScala
+    def fallback(file: File) = asBinary(file).orElse(asText(file))
+    def getContents(ref: VirtualFileRef): Option[AnalysisContents] =
+      val path = converter.toPath(ref)
+      val file = path.toFile()
+      try
+        val attrs = Files.readAttributes(path, classOf[BasicFileAttributes])
+        if attrs.isDirectory then fallback(file)
+        else
+          val lastModified = attrs.lastModifiedTime().toMillis()
+          val sizeBytes = attrs.size()
+          getOrElseUpdate(ref, lastModified, sizeBytes)(fallback(file))
+      catch case _: NoSuchFileException => fallback(file)
     for
       ref <- metadata.get(Keys.analysis)
-      file = converter.toPath(VirtualFileRef.of(ref)).toFile
-      content <- asBinary(file).orElse(asText(file))
+      content <- getContents(VirtualFileRef.of(ref))
     yield content.getAnalysis
 
 end BuildDef