diff --git a/internal/cache/s3.go b/internal/cache/s3.go
index d1a0f7e..3595b5e 100644
--- a/internal/cache/s3.go
+++ b/internal/cache/s3.go
@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"net/textproto"
 	"os"
+	"runtime"
 	"time"
 
 	"github.com/alecthomas/errors"
@@ -24,12 +25,14 @@ func init() {
 }
 
 type S3Config struct {
-	Bucket        string        `hcl:"bucket" help:"S3 bucket name."`
-	Endpoint      string        `hcl:"endpoint,optional" help:"S3 endpoint URL (e.g., s3.amazonaws.com or localhost:9000)." default:"s3.amazonaws.com"`
-	Region        string        `hcl:"region,optional" help:"S3 region (defaults to us-west-2)." default:"us-west-2"`
-	UseSSL        bool          `hcl:"use-ssl,optional" help:"Use SSL for S3 connections (defaults to true)." default:"true"`
-	SkipSSLVerify bool          `hcl:"skip-ssl-verify,optional" help:"Skip SSL certificate verification (defaults to false)." default:"false"`
-	MaxTTL        time.Duration `hcl:"max-ttl,optional" help:"Maximum time-to-live for entries in the S3 cache (defaults to 1 hour)." default:"1h"`
+	Bucket            string        `hcl:"bucket" help:"S3 bucket name."`
+	Endpoint          string        `hcl:"endpoint,optional" help:"S3 endpoint URL (e.g., s3.amazonaws.com or localhost:9000)." default:"s3.amazonaws.com"`
+	Region            string        `hcl:"region,optional" help:"S3 region (defaults to us-west-2)." default:"us-west-2"`
+	UseSSL            bool          `hcl:"use-ssl,optional" help:"Use SSL for S3 connections (defaults to true)." default:"true"`
+	SkipSSLVerify     bool          `hcl:"skip-ssl-verify,optional" help:"Skip SSL certificate verification (defaults to false)." default:"false"`
+	MaxTTL            time.Duration `hcl:"max-ttl,optional" help:"Maximum time-to-live for entries in the S3 cache (defaults to 1 hour)." default:"1h"`
+	UploadConcurrency uint          `hcl:"upload-concurrency,optional" help:"Number of concurrent workers for multi-part uploads (0 = use all CPU cores, defaults to 1)." default:"1"`
+	UploadPartSizeMB  uint          `hcl:"upload-part-size-mb,optional" help:"Size of each part for multi-part uploads in megabytes (defaults to 16MB, minimum 5MB)." default:"16"`
 }
 
 type S3 struct {
@@ -53,12 +56,24 @@ var _ Cache = (*S3)(nil)
 // Metadata (headers and expiration time) are stored as object user metadata. The implementation
 // uses the lightweight minio-go SDK to reduce overhead compared to the AWS SDK.
 func NewS3(ctx context.Context, config S3Config) (*S3, error) {
+	// Set defaults and validate configuration
+	if config.UploadConcurrency == 0 {
+		// #nosec G115 -- n is guaranteed >= 1. I was unable to satisfy all linters.
+		config.UploadConcurrency = uint(max(runtime.NumCPU(), 1))
+	}
+
+	if config.UploadPartSizeMB < 5 {
+		return nil, errors.New("upload-part-size-mb must be at least 5MB (S3 minimum part size)")
+	}
+
 	logging.FromContext(ctx).InfoContext(ctx, "Constructing S3 cache",
 		"endpoint", config.Endpoint,
 		"bucket", config.Bucket,
 		"region", config.Region,
 		"use-ssl", config.UseSSL,
-		"max-ttl", config.MaxTTL)
+		"max-ttl", config.MaxTTL,
+		"upload-concurrency", config.UploadConcurrency,
+		"upload-part-size-mb", config.UploadPartSizeMB)
 
 	// Create default transport for credential chain
 	defaultTransport, err := minio.DefaultTransport(config.UseSSL)
@@ -277,6 +292,18 @@ func (w *s3Writer) upload(pr *io.PipeReader) {
 		userMetadata["Headers"] = string(headersJSON)
 	}
 
+	// Configure upload options
+	opts := minio.PutObjectOptions{
+		UserMetadata: userMetadata,
+	}
+
+	// Enable concurrent streaming for multi-part uploads if configured
+	if w.s3.config.UploadConcurrency > 1 {
+		opts.ConcurrentStreamParts = true
+		opts.NumThreads = w.s3.config.UploadConcurrency
+		opts.PartSize = uint64(w.s3.config.UploadPartSizeMB) * 1024 * 1024 // Convert MB to bytes
+	}
+
 	// Upload object with streaming (size -1 means unknown size, will use chunked encoding)
 	_, err = w.s3.client.PutObject(
 		w.ctx,
@@ -284,9 +311,7 @@ func (w *s3Writer) upload(pr *io.PipeReader) {
 		objectName,
 		pr,
 		-1,
-		minio.PutObjectOptions{
-			UserMetadata: userMetadata,
-		},
+		opts,
 	)
 	if err != nil {
 		w.errCh <- errors.Errorf("failed to put object: %w", err)
diff --git a/internal/cache/s3_test.go b/internal/cache/s3_test.go
index 2e351c1..cc4df78 100644
--- a/internal/cache/s3_test.go
+++ b/internal/cache/s3_test.go
@@ -145,11 +145,12 @@ func TestS3Cache(t *testing.T) {
 		t.Setenv("AWS_SECRET_ACCESS_KEY", rustfsPassword)
 
 		c, err := cache.NewS3(ctx, cache.S3Config{
-			Endpoint: rustfsAddr,
-			Bucket:   rustfsBucket,
-			Region:   "",
-			UseSSL:   false,
-			MaxTTL:   100 * time.Millisecond,
+			Endpoint:         rustfsAddr,
+			Bucket:           rustfsBucket,
+			Region:           "",
+			UseSSL:           false,
+			MaxTTL:           100 * time.Millisecond,
+			UploadPartSizeMB: 16,
 		})
 		assert.NoError(t, err)
 		return c